The vent shrubite split from its ancestor and moved to Otter Vents. There it adapted to the extreme heat of the vents by evolving a thicker shell. The additional pressure meant it became even more "squaty" in size. Its now has developed larger filtering holes along the creases in the shell. Due to the large amount of sulfur in the water it now takes advantage of this abundant resources and metabolizes it. Any excess waste is squirted out of the top.