Alien trees? No, those are corals in the IMAG's Coral Reef tank! Corals may look like plants or stones, depending on their species, but they are actually tiny invertebrate creatures called polyps that live together in colonies. Some form hard exoskeletons of calcium carbonate; these skeletons form the reefs you may be familiar with. Other 'soft' corals become the plantlike, waving forms that fill the reefs. Together, they form key marine habitats that fill our fisheries, beautify our waters, and