From Creatures Wikia
Creatures 1 Incubator
The Creatures Incubator is a large, square machine with two windows on the front, along with a small nest inside where the egg is placed. In the original game, it is unmovable without cheats, but in C12DS, it can be picked up by the hand and moved.
Creatures 2 Incubator
The Incubator featured in Creatures 2 resembles a large, sphericle pod with a single, circular window. When an egg is placed inside, the lid of the pod closes, and a variety of coloured lights flash inside as the egg hatches.