A Black Sea Cucumber, a sea creature know in Thai as pling thalae dam. This one was observed off the coast of Koh Samet (fig.). Though its skin is entirely black, it often has sand adhering to it.

In the water, it shrinks and stretches in size as it moves about over the sea bed. However, if it moves along with the tides and wanders too close to shore, it might become trapped on the beach once the ebb sets in, where it is at risk of becoming dehydrated (fig.).