Neocrinus decorus, like most echinoderms, is composed of numerous calcite plates which are arranged into different organs.
N. decorus is divided into 3 sections:
- The stem:
- raises the calyx and arms above the sediment and is composed of a stack of numerous 5-sided star-shaped plates.
- bears flexible, finger-like appendages called cirri that are used to reattach itself to the substrate after moving.
- The calyx (body or theca):
- is formed of 2 bands of 5 plates that form a cup-shaped body, from which the bases of the arms arise.
- is covered on top by numerous small polygonal plates. The mouth and anus are found on this surface.
Neocrinus decorus calyx with mouth, food groove and anus.
- 5 originate in the calyx but these frequently divide, similar to tree branches, so that there may be up to 40 arms in total.
- are formed of stacks of U-shaped calcite plates
- bear numerous projections called pinnae (like those of a fern frond). It is on these pinnae that tube feet, covered in mucus, extend into the water and catch plankton.
- are moveable
- are usually arranged in a parabolic fan to collect food
- can be used for crawling (dragging the stem behind it).