I believe your are talking about a 3D figure called a Mobius strip. It is a strip of paper that has a half-turn in it that causes technically a one sided figure.
A 3D semi circle
circumference
a sphere?
A piece of an edge of a circle is called an ARC.
The half of a diameter of a circle is known as a radius.
A twisted pantyhoe.
We call it a "semi-circle"
twirled, spin, move in a circle.
A semi-circle
Concentric Circles?
We call it a circle.
The Twisted blade that helps a plane fly and a ship move is call a propeller.
A circle with three dimensions is sphere.
square, circle, triangle, twisted triangle, pentagon, twisted pentagon, brick, wall, twist, corkscrew, quad, tornado, cobra, twisted cobra, butterfly, staircase, diamond braid, zipper, fishy pull, candy stripe
a semi circle? common sense
Inscribed
A quarter of a circle or a quadrant!