What Do You Call Animals That Lay Eggs?

Egg laying is common to all species of birds and most reptiles, though several species of snakes and lizards are viviparous. Most fish and amphibians are oviparous as well. Among mammals, only the platypus and four species of echidna lay eggs. There is a third mode of reproduction, called "ovovivipary" in which embryos develop inside eggs that are held within the mother's body, until they are ready to hatch.