don't no
a face
sphere
Possibly a face - or an edge. It would help if the question was properly phrased.
you call it a edge
A sphere
A blob.
a line
A Moebus strip.
Circle. Sphere.
It is a face.
Mobius strip
An edge.
To answer this question more details need to be provided. For example one a 3D shape one side is called a face.
A face value in maths is the out-side of the shape, as to say the face of a shape. The face value is the sides of a shape.
The side
The faces in a 3-D shape (polyhedron, for example) are bordered by edges.