“…• each face has the same area, • the four faces are congruent triangles, • every edge has the same length as the opposite (skew) one, • the circumscribed parallelepiped, each of whose faces contains exactly one of the tetrahedral edges, is a box (Figure 1). Note that the existence of such a circumscribed parallelepiped C is assured by the well-known fact that two skew lines (respectively skew edges of a tetrahedron) determine a unique pair of parallel planes (respectively faces of C), These and more characterisations of equifacial tetrahedra can be found in [7,8,9,10,11,12], and not so obvious characterisations (even within the family of all convex polyhedra) are given by [13] and [14].…”