That would be a triangular pyramid.
A pyramid perhaps
A triangular prism can have a square or triangular base, but faces are normally triangles. (I think)
It depends on the shape of the base, but yes it has at least 3 triangular faces!(yes)
A Triangular Pyramid, 3 faces, 1 base.
A pentagonal pyramid
tetrahedra (a pyramid with a triangular base)
A square pyramid.