Complex sentence: However, there are two different ways of smoothing subsets of the edges of the Reuleaux tetrahedron to form Meissner tetrahedra, surfaces of constant width which were conjectured by to have the minimum volume among all shapes with the same constant width; this conjecture remains unsolved.
Split into simpler sentences: However, there are two different ways of smoothing subsets of the edges of the Reuleaux tetrahedron to form Meissner tetrahedra, surfaces of constant width. These shapes were conjectured by to have the minimum volume among all shapes with the same constant width, but this conjecture remains unsolved.