Crind

A crind is a shape formed as the intersection of two perpendicular cylinders. It is the crind product of a square and a dyad. It has 4 curved sides for its surface, meeting at two common points.

The crind is abstractly equivalent to a square hosohedron.

Coordinates
The points on the surface of a crind can be given by max(x2+y2)+z2 = 1.