scutoid

A scutoid is a geometric solid between two parallel surfaces. The boundary of each of the surfaces is a polygon, and the vertices of the two end polygons are joined by either a curve or a Y-shaped connection. Scutoids present at least one vertex between these two planes. Scutoids are not necessarily convex, and lateral faces are not necessarily planar, so several scutoids can pack together to fill all the space between the two parallel surfaces.

"A scutoid is geometric solid between two parallel surfaces"