a sphere
a giant or small cone
In geometry, the only shape that has one surface is a plane.
A cardioid is one possibility. See link, below.
sphere
Cylinder
Cylinder
sphere
a sphere
A sphere.
The surface of an infinite cone.
The surface of a shape is dependent on its shape and dimensions.
a cone
cylinder
It is a hemisphere.
Surface area of a shape depends on what shape you have in mind.
Maybe its the shape of cylinder which has 2 congruent sides and 1 rounded body.