A cardioid is one possibility. See link, below.
In geometry, the only shape that has one surface is a plane.
A flat one! (:
A cone.
A cylinder
yes it has a flat bottom surface and one vertice
one
a cone.
Well it has one edge, one face, one base(the face that the shape sits on), and one vertice.
A cone.
none!all shapes are flat
half a sphere
There can be no such shape. If there were a shape with n flat surfaces, then if you sliced off one vertex, you would have a shape with n+1 flat surfaces. So it is always possible to add one more flat surface.
The cone has only one vertice. It is the only three dimensional shape that has this characteristic. All others have more than one vertice.
A cone.
A Cylinder
A square is a 2 dimensional shape with one flat surface area whereas a cube is a 3 dimensional shape with six flat surface areas.