Sea snails and a Horseshoe crab
Much like the Horse shoe crab and its eggs. 100 Baht = 2.95 € a kilo. But there isn't much to eat and the eggs, a matter of taste. The spezie of the crab is known to to be very old, the earliest horseshoe crab fossils are found in strata from the late Ordovician period, roughly 450 million years ago.
I like the snails cooked in a curry sauce and eaten out with a sharp pointed fork. The flesh is excellent and taste better than the French Burgundy snails.