coelenterate

The aloofness displayed for each other by members of the marine coelenterate species of Gorgonaceae suggests that mechanisms for preserving individuality must have existed long before the evolution of immunity.

For example, cells in the coelenterate Hydra form them.

Most of the main groups of the animal kingdom—arthropods, brachiopods, coelenterates, echinoderms, molluscs and even chordates, the branch from which vertebrates went on to develop—are found in the fossil beds of the Cambrian.