Eocrinoids

Eocrinoids are a form of ancient sea creature, a class of echinoderms. While they are sometimes easy to mistake with crinoids, they are different creatures.

Eocrinoids lived between 520 and 420 million years ago, and are extinct. They were more primitively stalked, and had less complex ‘arms.’

Crinoids first appeared 485 million years ago, and still exist today. They are more complex, and usually (but not always) have a defined stem, calyx, etc.