This is a mystery piece. I think it is part of a larger assembly and that you have only a part of the whole. If you had the remainder, its use might be more apparent.

Some features of the bigger piece:

It has a rim with a turned up edge and a number of holes around the perimeter. These indicate that it was bolted to something else.

Also on this rim/flange are two sets of tabs with holes through the ends. These tabs are not decoration, but were put there for a purpose. Likely, a rod, pin, or bolt ran through these holes. Another possibility is that a wire form bail was fitted through these holes and served as a spring clamp to hold this piece to something else.

Is there any hole in the solid piece on its bottom?

Part of a heavy duty carbide headlight such as from an early truck or train? The right angle suggests this.

Industrial disposal flange and stopper?

Antique floor drain with some crude filtering?

Could we see other angles? Is it magnetic? Iron? Steel?

Looks more like plumbing than anything to me.