WALKING PYRAMIDS

Pinnarthrus mobilis is a species of specialized herbivorous crab from Desma. This species inhabits the beaches of a northwestern peninsula of Neoprimaria. It is rather common and easily recognizable for its pyramidal-like top, and yellow and black legs. It is related to other crabs like Pastocaris and Geocaris, implying perhaps that this group of herbivorous crabs evolved early in this seeded world's history, when Eoprimaria and Neoprimaria were together in one singular continent.

This crab species patrols the shores of its range in search of algae, which are an abundant resource that comes to shore. It becomes a competitive pressure against the several snail species that have adapted to that coastal food source, and crabs are more adapted to move away from changing tides, so here, at least, crabs seem to be regaining a dominant role in beach combing lifestyles.