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Late Silurian
Rissan, Morocco
Scaphocrinites elegans is a crinoid, a term derived from the Greek krinon, meaning "lily." Though they do resemble lilies, crinoids are not plants but invertebrate animals ƒ stemmed echinoderms, relatives of the sea urchin, starfish, sand dollar, and sea cucumber. During the Paleozoic era, a great many varieties of stemmed echinoderms lived in the sea. Some were free-floating; others were rooted to the bottom of the sea, with a swaying stalk that supported a vase-shaped body (theca). Extending upward from the theca were brachioles or branches, probably carrying finger-like cilia, which swept food into a mouth that faced upward at the apex of the theca. Part of a theca is seen at twelve o'clock in this photograph, with a clump of brachioles matted together in the lower half of the picture. The two columnar structures and the small cylinders at the top left are stems and pieces of stems. Ring-like structures similar to those in the human trachea gave stability to the stems, but because the stems were rigid, they had little flexibility.