They are mostly bottom-dwellers. The sound bounces off the object and some returns to the whale. The whale interprets this returning echo to determine the object's shape, direction, distance, and texture. Bats also use echolocation. Reptiles are ectothermic.
Some animals hatch from eggs.
Fossilized eggs from some prehistoric animals have been found. An embryo is a very young, unborn organism. An endangered species is a group of animals that is dwindling in numbers and may go extinct soon. Many species of baleen whales are endangered. Birds and mammals are endothermic.