My Coral: both sides, found many years ago hunting in Florida
Corals (or more formally, Zoantharia) have mobile larvae that become sessile (fixed to one place) after a few days. They are marine animals related to jelly fish and sea anemones, but lacking a free-swimming (medusoid) stage.
They may have first evolved during the Precambrian and are still found living today. Some, like octocorals (the polyp has eight arms), are soft bodied and rarely preserved as fossils, but others secrete a hard calcarous skeleton and are thus important rock-forming organisms. We focus here on the three groups (or orders) of corals that are most frequently found as fossils — Rugosa, Tabulata and Scleractinia.