^o
~o o~
Trichobala tribozatetrahedrum has added a layer of cells in a triangle formation (see above) on top of the previous layer of triangular oriented cells, making an open-faced tetrahedron. Now, in addition to having a lumen (inner) and apical (outer) surface, there is a posterior/caudal (back/tail) and anterior/ventral (front/belly) surface/orientation. Perhaps this could be expanded to become a primordial body plan in the near future. And equally important, the cells lining the anterior/ventral side of each “face” can theoretically keep dividing and keep adding another layer to cells; in effect, it can grow longer anteriorly/ventrally (please see the picture below).
