It may be the closest scientists have yet come to creating Frankenstein’s monster. Living pieces of dozens of individual animals known as comb jellies have been fused together to create an array of new forms that, in some cases, survived for more than a week.

These chimeric animals are more than just physically connected bits of different individuals, says Leonid Moroz at the University of Florida. Their nervous systems also fuse together, creating entities that heand his colleague Tigran Norekian, also at the University of Florida, call…