Evergrowing Sasule

The evergrowing sasule split from its ancestor, the sasule. A flaw in a sasule prevented the complete split during binary fission. That same sasule grew in length as the same thing happened over and over again. As it still needed to swim to go to food, the body shape got in the way, so it became streamlined. It swam throughout the ocean, growing bigger and bigger, when something happened in the tail region. A cell had become detached from the main body. That cell then became a separate individual, and was entirely functional. It then would repeat what happened to its parent, growing and growing, until the back end became so thin that it broke off. In this manner, an evergrowing sasule individual won't die in the official sense, but the growing, replacing, and breaking off of cells does make the individual different after about ten generations.