Cystoids

Cystoids were diverse, usually stemmed echinoderms. The globular or pear-shaped theca is covered by plates and pierced by slits or pores. The slits are continuous or disjunct across the sutures between plates; the pores pierce the plates. At the top of the theca are inconspicuous food grooves leading to a central mouth; the food grooves and mouth are sometimes covered over by plates. Slender arms for feeding were attached along the food grooves, but they are almost never preserved. The anus is located at the top of the theca, near the mouth.