All 12 sides are straight! This is a 2 dimensional object. * * * * * A dodecahedron is NOT a 2 dimensional object so the above answer is utter nonsense. A dodecahedron has pentagonal faces.

A dodecahedron is a (simply connected) 3-dimensional shape with 12 polygonal faces. There are approx 6.4 million topologically different convex dodecahedra, plus concave ones.

No, a dodecahedron is a 3-dimensional shape. Some of the 6.4 million topologically distinct dodecahedra have only triangulat faces, there are many more in which some faces, but not all, are triangular.