The sphere.
It is called a face.
a face.
cone
The answer is a cone
a face
A conic section.
a pyramid
It can be a sphere, a spheroid, an ellipsoid, etc.
A polygon is a many sided 2-dimensional figure, and thus could never be "solid" Alternatively, it could be "one face that is a polygon". In that case the solid could be like a pyramid that morphs into a cone or a part-sphere. The base would be the one polygon, the other face would not.
A square pyramid
NO!!!! A square is a two-dimensional shape, drawn on a surface. It has only one face, viz. the surface that it is drawn on. It has four sides, and four angles. A solid 3-dimensional figure with 6 congruent faces is a 'CUBE' . Each face of a cube is a 'square'. That is probably were you are confused!!!!!
A Sphere only has one face and no verticies.