Tilepillar

The Tilepillar replaced its ancestor. It inhabits all the south-most waters of Sagan 4's Oceans, using the cold-water currents to travel long distances. It prefers warmer water, though it can survive in the polar regions.

It has lost most of the plating on its appendages, instead having a thick domed shell on its back. The biggest change is its tail, which has become a long muscular paddle. It uses its tail to propel itself through the water, using its flipper-like front fins to steer; its hind limbs have gotten smaller out of disuse. If an individual finds itself on land, it will use its paddle-tail to push itself along the ground.

Its reproductive behavior is different from its ancestor. On the winter solstice, tilepillars will congregate on whatever temperate beach they are closest to. They will then mate and lay their froglike eggs in the surf.