The most familiar members are sea anemones and corals. Temperate zone anemones crowd the intertidal rocks. Their powerful stinging cells can capture crabs and small fish. Cloning is practiced by the rock covering that spreads as individuals simply pull in two. Tropical anemones often are accompanied by small anemone fish that avoid triggering its host's stinging cells.
Stony corals produce limy cases that build the reef.
Soft corals flex, their polyps encased in a common skin. The ones shown are from the coral reefs of New Guinea and Hawaii.