This is not the half of it - there are probably three times as many food items available on the reef every two weeks of every lunar month throughout the year, when the low tide is strong, around about mid-day, regular as clockwork, and more food is exposed. 

Popokon
Chama iostoma                              
This from a different family of rock oysters is usually attached to a rock, but can also get itself coated with stone, so it resembles a tough little pebble. They are not true oysters, but they do taste better than mere Tipay-Tipay.

Lambajang
Clam - Ctena bella 

These are not only good to eat, but if you grind off the outer rind, you get a wonderful sunset pink/yellow shell. Add a few bits to a pair and you get a coin purse. I sell them to natives in Majorca.

Univalves - 'Snails'

Ganga
Spider Conch - Lambis lambis 

Bangkoyon
Abalone - Haliotis diversicolor
These are a lot smaller than the huge Californian, South African or New Zealand (Paua) shells that Chinese people worldwide pay fortunes for, but they are still delicious. With only a bit of imagination, you could see Ms Homo erectus knocking one of these things off a rock with a multi-purpose Acheulian handaxe, and enjoying a pre-prandial seafood cocktail.

Samong
Top Shell - Tectus fenestratus

Small species of Trochus, like these, provide only a tiny snack - the larger species have been hunted relentlessly for centuries. Your grandfather's dress shirt probably had 'pearl' buttons made from Trochus niloticus, and, to this day, Indonesian fishermen 'invade' Australian waters - as they've done for at least 500 years - to find the commercial Trochus shells.

Dugingey
Vase Shell - Vasus turbinellus


Tasty, but a bit picky - you have to pick out the body, then get rid of the horny operculum, and after all that, there is not a lot left. 

Pajong (Umbrellas)
Limpets - Patelloida saccharina

Well, these are no delicacy but they are very, very available - on every rock-top at any low tide. They are very tough customers, but no less nutritious than any other shellfish. They're worldwide, so you could try one out in your own country almost anytime; but make sure your pick is far away from a sewage outfall or a major industrially-polluted river - these things browse on the latest arrivals on a seaside rock surface, and some of those things might have come from your own bathroom or kitchen sink ( or even worse, your neighbour's or the factory down the road).

Hilla-Hilla
Nudibranchs - Phyllidia spp.
Shell-less Limpets? These things move about on rocks (remarkably fast for a snail - I suppose they have to at times, not having a shell to protect them from the sun). They are tough and rubbery, and have to be parboiled before cooling to make a kinilaw (raw seafood salad, in vinegar and spices) -

see Kinilaw - The Art of Natural Food 

Chiton
Mopalia sp?

This isn't really a food item, but I included it here because it is a perfect example of convergent evolution. Chitons are among the most primitive molluscs, and have co-existed with echinoderms (sea urchins) for about 350 million years. Even after all that time, for a primitive snail to grow spines almost exactly like a sea urchin's is a fact somewhat to be wondered at.

Stomatella sp
This isn't an important food item either, but it just cried out to be included, as a small animal that has evolved over millions of years to become a mobile poached egg.

Sea Urchins

Balaw
Sea Urchins - Echinometra sp

Nearest to the kind of 'oursins' you get in Parisian restaurants, with short, thick spines - I have to confess that the coldwater versions do taste better (but possibly because they are a lot more expensive).

Saliwake
Sea Urchins - Salmasis bicolor
Really not to my taste; possibly because I often buy (for 80¢ a glass) the male and the female bits mixed together. They make an impossibly creamy sauce-like mixture, with too much of everything. The five orange rays are the eggs or sperm.

Bilisong
Pencil Urchin Heterocentrus spp

Also a great eat,  and spectacular when they come out of their little clefts in the reef in the early evening, and wave their six-inch spines around like a mob of orchestra conductors. You could almost swear they know music - maybe not Bach, but Elvis, certainly.

Tajum - Sea Urchin (Nasty, Black, Long-spined) - 
Diadema setosum   

Urchin Spines - These things are so common (especially on storm-damaged reefs) that one forgets about them - unless you step on them and get a spine in your flesh. If you do, the very best answer is to piss on the affliction immediately, even if you feel a fool standing out on a reef, holding one leg and your whatsit, and trying to hit the spot. It's easier for women, which is why they were probably given the job (and still have, now) of gathering these things.

Now, this is it. They have very large, solid, tasty ovaries, full of good things like iodine and a few omega fatty acids as well. They are delicious. 
If you've ever tried soda nayyeh (raw fresh lambs' liver) in Lebanon, you'll understand. This tastes just about the same, but with the whole world's sea origins in it. 

Sea Cucumbers

Batunan 
Sea Cucumber  - Holothuria sp
 

Found under every other rock in shallow water - they're also very good to eat - flavour very 'marine' and texture like a fresh rubber band, crunchy. Worth trying. Once.

Sea Cucumbers are hugely popular in China, and before you wrinkle your nose in disgust, please remember there are about 1.5 billion more of them than us. There are probably more than 20 times more Chinese people than you who think these are great delicacies.

To you (and me) these things may look like turds on a table. But  the market stall owner who carefully laid out each of these small sun-dried offerings, was expecting grand rewards. The names are from top L: Lawayan, Cortido, Hanginan, Kati, Bulibuli, Labuyo, Pajula, and Hanginan again.  

Bayat Uwak
Sea Cucumber - Thelenota ananas            

This is the nasty black common sea cucumber that looks like a large dog has just visited that particular spot. It is just about edible, but very far down the line, as sea cucumbers go - just too common to be worthwhile, and not very tasty at all. When you pick them up, they squirt out a stream of viscous white 'gum', that dries and shrinks in the sunlight, encasing you in a sort of tourniquet.

But even this can be used - fishermen wrap their feet in it as protection when walking on the reef.

Crustaceans

Slipper Lobster

Kupapa Slipper Lobster - Parribacus antarcticus  


Not often found hiding on the reef, but we were lucky. They are a treat - almost as good as a 'real' lobster, so I kept it for my supper.

Richard Dawkins has quite a lot to say about this particular creature in his book 'Climbing Mount Improbable'. The front end looks almost like the back end of any other lobster, and he proposes that, sometime in the past, an ancestor underwent a homeotic mutation (where a body part grows in the wrong place) and grew part of its tail where its antennae should be. It now has a very good survival tactic - lobsters escape by clapping their tails under them, and shooting backwards very fast. If a clever predator knows this, and aims at the 'tail' end of this fellow, as he thinks, it will shoot straight backwards, away from him.

Wing-Wing
Spiny Rock Crab - Thalamita crenata
You need about a dozen of these to make a tasty soup. 

The 'face' on its back is popularly supposed to be a memorial to a drowned fisherman or sailor.

But you should be wary of other small shore and shallow water crabs - some of them are poisonous.

Wing-Wing

Also applies to other small edible crabs - these come from the brackish water mangroves at Tawin-Tawin.

Well, we didn't get any of the following that particular day, but I thought I would park them here, until they get a home of their own.

Kayabang
'Coconut Crab' - Cardisoma hirtipes

 

Kayabang live in the coastal coconut groves, digging large holes, that, like earthworm casts, help circulate and aerate the soil. 

Once a month, at full moon, dozens of kayabang come out of the coconuts, and head straight to the beach to mate and lay their eggs. They march purposefully in an almost straight line, often through the town. At the last full moon, one came straight through a group of us sitting outside Lourdes' Food House, only to be trapped by Big Marty's foot. He told me it made a good part of his breakfast. The local people go to the beach at full moon with flaming torches made from dried coconut leaves, and pick them up by the dozen.

Karaykay 
Ghost Crab - Ocypode ceratophthalmus

Retreats to its hole on the sandy beach just as you walk along. If you were quicker and smarter than I am, you could maybe catch a dozen or two for lunch.

Tatos
Coconut Robber Crab - Birgus latro

A kind of hermit crab that has taken to land-living and gigantism. These are now rare in Siargao, although there are occasional reports of catches. I have caught a juvenile one, still living in a large Triton shell, on Mamon island, about 45 minutes out from here. As he grew too big for that, he would have taken up the 'naked' existence of the adults. They do grow quite large, as you can see from this one attacking a fully-grown coconut.

Amimintik
Mantis Shrimp - Odontodactylus sp

These are quite delicious - but be careful of their front legs - they 'snap' very quickly and are designed to catch fish or break snail shells. This one's 'elbows' show it is a snail breaker.
You can often hear them snapping under water.