Hoops. Don't know where it came from, but I got it years ago from a manufacturing company, Donnelly Corp--now part of Magna Corp--that makes products from glass
A flat glass does not form any image. It simply allows light to pass through without bending or focusing it, so no image is formed.
circles
There are 2 flat surfaces, both are circles.
nail, glass shard, rock, pin
they are formed at the point of contact of lens and glass plate
Circles, squares, rectangles, and triangles are solids that have a flat surface.
Cylinder
A pane of glass is a thin, flat piece of glass.
A Cocktail Glass is also sometimes called a Martini Glass. Martini Glasses have a flat base with a bowl on top of a stem and are used to serve Cocktails.
The lines in an air wedge result from interference of light waves that have traveled different distances. The resulting interference pattern creates alternating dark and light bands. In Newton's rings, the circles are formed due to interference of light waves reflected between a convex lens and a flat glass surface. The varying thickness of the air gap creates a series of concentric circles of alternating dark and light fringes.
It is a mirror or a looking glass
My guess would be a cylinder.