The shape in question is called a square pyramid.
It is the base/face of a certain shape, as in a square, it would be the bottom line(the one on/closest to the ground).
The shape of the base of a cube would be a square.
A shape with a square base and four triangular sides is a pyramid.
A pyramid has 1 square base.
A square pyramid.
A Square Pyramid.
A square based pyramid is a three dimensional shape with a square base, and four triangles (one from each side of the base) that meet at a point above the base. The shape has 5 vertices, 5 faces and 8 edges.