And the squid still swims around with its gladius intact, and the octopus with its stylets -- reminders of the history they share with the shelled creatures of the past.
And scientists know that it was an echinoderm based on the material that made up its internal skeleton - a calcium carbonate matrix called stereom - which is a feature shared by all of the members of this group.
But there's no evidence that it had stereom - the stuff that makes up the internal skeleton of all echinoderms, so it could've just been another round animal like a jellyfish or a sponge.