Corals of the phylum Cnidaria and class Anthoza are marine animals related sea anemones that lack a free-swimming (medusoid) stage. They have mobile larvae that become sessile (fixed to one place) after a few days.

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The earliest corals appeared in the rock record during the Cambrian, more than 500 million years ago, and are still found living today. Some, like octocorals are soft bodied and rarely preserved as fossils, but others secrete a hard, calcareous skeleton and are important rock-forming organisms. 

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