Gogia kitchnerensis
Eocrinoid
Middle Cambrian
Spence Shale
Antimony Canyon, Brigham City, Utah, USA

71mm eocrinoid on 125mm slab.

Eocrinoids are one of the earliest-known groups of echinoderms.  The name implies that they are ancestral to crinoids but they may not be despite the fact that both groups have very similar structure (holdfast, stalk, plated body, arms) and crinoids appear to be more advanced forms.  Eocrinoids appeared in the Early Cambrian but became extinct by the end of the Silurian.

Nice specimen with stalk, cup, and arms preserved.