Cladochonus sp. - a tabulate coral
Crinoids being gregarious animals attracted the attention of other marine organisms. One such marine animal is the Tabulate coral - Cladochonus. As you can see in the photo to the right, this particular coral attached itself to the stem (stalk) of the crinoid thus enabling access to a better food supply. This is a good example of a parasite behaviour in the fossil record.
As the coral grew it is believed that Cladochonus had an undesirable effect on the living crinoid; either harming it or perhaps eventually killing it.
Other marine organisms sometimes found with the crinoid include the coral Emmonsia and the gastropod Platyceras. Emmonsia has been known to engulf the stem while the gastropod Platyceras seems attracted to the calyx, particularly the area by the anul tube. It is unclear as to wherther this relationship is symbiotic or parasitic.