Everybody loves deltahedra! That is, a 3-D solid whose faces are all equilateral triangles. A strictly convex deltahedron is one whose edges always curve inward (i.e. they are round; as opposed to concave where they curve outwards). Strictly convex means that no two faces can be coplanar.
"We have the tetrahedron, the cube, the octahedron to the dodecahedron and icosahedron cuz of you!"
https://www.youtube.com/watch?v=FqCZhSIXcv4&ab_channel=D%21NG