Worms lacked such elegance, but Eternons had fitted them with elaborate circulatory, digestive, and reproductive systems. In addition, an elementary brain centralized information processing. The concept was so promising that this "worm technology" was to be continuously upgraded to higher organisms.

At first, the animal kingdom looked rather squashy. Octopuses and squids had just been taken off the drawing board and put into production. Some versions reached great size, but all remained soft-bodied creatures. Snails, clams, oysters, and further mollusks, on the other hand, featured a very hard shell to house their soft organs. The next logical step was an articulated skeleton, more versatile than a rigid casing.

Some Eternons chose the external skeleton, giving birth to the most diversified group on Earth: the arthropods. Lobsters, shrimp, crabs, spiders, scorpions, and a huge variety of insects, represent three-quarters of all animal species today. Arthropods introduced notable innovations, including wings and flight. Their high reproduction rate also enabled Eternons to start experimenting with complex social behavior.

A number of Eternons, however, had opted for an alternate method to brace their constructions: putting organs around instead of inside the skeleton. Starfish and sea cucumbers paved the way for the chordates, the group to which we belong.