CORALS
Corals (Kingdom Animalia, Phylum Cnidaria, Class
Anthozoa) are marine creatures. They’re essentially colonies of sea
anemones that make a skeleton, usually mineralized. The hard skeleton is
relatively easy to preserve, so corals are well represented in the fossil
record. During the Paleozoic, common coral groups included the tabulates,
the rugosans, and the heliolitids. All of these groups went extinct at
the end-Permian mass extinction. Post-Paleozoic and living corals are all
representatives of one group - the scleractinians. A lesser known group
of corals is the octocorals (a.k.a. alcyonarians), known from the
Cambrian to today.
Corallium rubrum (Linnaeus, 1758) - the red coral (a.k.a.
precious coral, noble coral) is a spectacular example of modern
octocoral. Polished fragments have been used as organic gemstones.
The skeleton is aragonite (CaCO3) mixed with reddish-colored organic
compounds. Corallium rubrum occurs in the northeastern Atlantic Ocean
and the Mediterranean Sea. (public
display, Field Museum of Natural History, Chicago, Illinois, USA)
Classification: Animalia, Cnidaria, Anthozoa, Octocorallia,
Gorgonacea, Corallidae