Super example of the rare primitive echinoderm, Ctenocystis. Found in a Burgess Shale type fauna, these odd little echinoderms seem unique to the Middle Cambrian of Utah. As I said, I've seen them classified as carpoids. More complete specimens more clearly show the tail, though you can see the outline of one here. My specimen is 3/16 inch long on 2 x 2 ½ inch matrix. The matrix piece is actually the top of a Spirophycus burrow making for a unique association of the two fossil types.