On a dive with Dave Barnes I measured the center disk of these little creatures with calipers in the IBIS grids. I have also collected quite a few of them for different projects. If one of their legs breaks off they can just grow another one. They hide really well in the sediment so you sometimes have to look closely to see an outline of them in the sand and then whaft away the sediment. They can also move pretty quickly and can be found at 5 to 1,266 meters which is a pretty large range. I think they look like little spaceships underwater!

For more information on this species of brittle star click here.
http://peterbrueggeman.com/nsf/fguide/echinodermata11.html