In the first of our series, “Dear Dr. Blue,” Dr. Sylvia Earle answers a simple query from a reader, “What is this?” ~ Ed.
You squished a poor defenseless sea cucumber — a holothurian, member of a class of echinoderms that also includes starfish, sand dollars, brittle stars and sea urchins.  Like other echinoderms, these animals have 5 part radial symmetry and a water vascular system that powers tiny tube feet that cover the skin and make it possible for them to creep along whatever they are sitting on (yes a creepy critter!)
In cross section the five part arrangement is evident, and in their five frilly feeding arms that extend from the front end.  Like an earthworm, most sea cucumbers lumber along, artfully picking up yummy bacteria and algae rich sand, digesting the good bits and extruding the scrubbed material out the other end.…