Crinoid Stem Fossil
kungurcave.com -Crinoid Stem Fossil Some fossil crinoids, such as Pentacrinites, seem to have lived attached to floating driftwood and complete colonies are often found. Sometimes this driftwood would become waterlogged and sink to the bottom, taking the attached crinoids with it. The stem of Pentacrinites can be several metres long.
History, products, and more. Crinoid fossils contain pentaradial symmetry, meaning “five-fold”, a characteristic of echinoderms and is present in crinoids. They have three distinct sections, each showing the pentaradial symmetry. These sections are the segmented column or stem, the calyx which contains the digestive organs, and the arms which filter food from the surrounding water. Most crinoids attached themselves to the ocean floor, although there is evidence in the fossil record of free swimming species.
Crinoid Stem Fossil s echinoderm sea lilly. Crinoids are commonly known as sea lilies, though they are animals, not plants. Crinoids are echinoderms related to starfish, sea urchins, and brittle stars.
About crinoids. The crinoid column is also called a stem or stalk. The stem is made from disc-shaped pieces of endoskeleton which are stacked upon each other and are hollow in the middle. They are held together by ligaments which decomposed rapidly after death. The hollow shapes inside of the discs include: elliptical, circular, pentagonal, and star-shaped. Column discs which are square-shaped have 5 holes in them. Fossil discs are commonly found in Paleozoic limestone deposits.