👉 Hydrocorals are bivalve animals that live in saltwater environments, primarily found in marine habitats such as oceans and estuaries. They have a unique adaptation called "hydrogels," which allow them to float on water without sinking or sinking. These organisms are composed of two layers: the outer layer is made up of a soft calcium carbonate matrix, while the inner layer contains a gel-like substance that provides buoyancy and stability in saltwater environments.