Most eggs that are eaten by humans have a eggshell. there are multiple parts to the egg: the egg white, the egg yolk and various thin membranes, Every part of the egg is edible, although the eggshell is usually thrown away. Eggs are a good source of protein.
Roe and caviar are edible eggs produced by fish. They do not have an eggshell, since they hatch underwater. They also are much smaller and do not have a white or yolk.