This is just my personal opinion that this is probably the case.

I think it's a hollowed out resin tray.

It appears to be a tray carved out of a block of resin.

Very very beautiful

The surface is covered with fine scrapes and has been scraped down to a thickness that allows the bottom to be just barely visible.

It's a texture I've never seen before.

There is no inscription on it, so it is unclear how it came to be.

I think imagining that is one way to enjoy antiques.

Size

about ; φ250*H45mm