Hey, I was hoping someone could help me identify an invertebrate. Unfortunately I did not have a camera but will do my best to explain. There were 18 what appeared to be individual animals clustered together on a Sandy bottom, 10m deep in the Nicaraguan Caribbean sea. Each animal was 2inches long and about ½ inch wide. They varied from a light grey to browny green and had noticable lateral ridges/notches down the body like a sea cucumber. They appeared to be stationary and anchored into the sand by some kind of appendage. They reminded me of community caterpillars. I think they could be grub sea cucumbers (Pseudothyone belli) and maybe in their doliolaria stage. I can't find much information about them though. Any suggestions? Many thanks.