Like most echinoderms, Pentacrinites is composed of numerous calcite plates which are arranged into different body parts. Pentacrinites has 3 kinds of body part: arms, cup (calyx or theca) and stem. The stem consists of a stack of numerous 5-sided beads (or columnal plates) with a canal at their centre. The stem has flexible appendages (or cirri) that were used to attach an individual. These cirri themselves are connected to specialized columnals called nodals, leaving oval scars after breaking off. The cirri consist of diamond-shaped plates with a central canal, less flatted further from the stem.[4] The cup-shaped calyx is very small and consists of two bands of five plates. These are the bases of the five arms. The top of the calyx is covered by numerous small polygonal plates and the m