The Box Plant (Cista Caeruleus):
The Box Plant is more-or-less perfectly square, and has been so successful that the only organisms left in the world are Box Plants and small, needly predators resembling Spinnies. They consist of a densely folded mass of photosynthetic segments surrounded by a protective shell of overlapping blue plates. Any plants that do not conform to this model are rapidly killed off by the roving predators, who swarm amongst the Box Plants eating the dead, the deformed, and each other. The Box Plants appeared at roughly the same time as a circular version, but appear to have out-competed them.
When they first appeared around generation 360, I was surprised by the square shape, given that I hadn't intervened at all in the world (except for some parameters: 50,000 initial carbon and 0.01 mutation %), and even the initial organisms were randomly generated.
Download its genetic code.