Some possible answers: a sphere, a cone, a cylinder, a ellipsoid (end-on), a spiral (like fusili) are some examples.
circle
One possibility is a closed shape: a circle, ellipse, a closed wriggly shape.
A circle
A circle !!!!!!
When a circle is rotated about a line that lies in the same plane as the circle and does not intersect it, the three-dimensional figure formed is a cylinder. If the line is outside the circle and parallel to its axis, the result is a cylindrical shell. If the line is the diameter of the circle, the figure formed is a sphere. The specific shape depends on the position of the line relative to the circle.
circle
A circle.
because if it had 4 straight lines instead, we would call it a rectangle.
A zero sided shape technically isn't a shape. The definition of a shape is a closed figure with at least one points evenly going to another point. A circle is the figure with the least amount of sides because it has one side, which is considered the circumference of the circle.
A shape cannot have only one side because it would not be closed. A shape must have at least three sides to be a closed figure (no "gaps")
One possibility is a closed shape: a circle, ellipse, a closed wriggly shape.
A circle
A shape that when you draw a line on the shape and cut along the line you get two identical shapes. A circle is an example.
A circle !!!!!!
A circle.
Circle and semi-circle?
When a circle is rotated about a line that lies in the same plane as the circle and does not intersect it, the three-dimensional figure formed is a cylinder. If the line is outside the circle and parallel to its axis, the result is a cylindrical shell. If the line is the diameter of the circle, the figure formed is a sphere. The specific shape depends on the position of the line relative to the circle.