As the name might imply, this is a byproduct of a Tupperware mold. In this case a bowl.
It can be used by itself or with another piece making it an artistic garden composition.
There is a tile in the middle of the saucer under the tupperoid.
If the tupperoid is removed, the saucer can still be interesting by itself.
Refer to the ‘concrete for the home’ category for tips on concrete, tools and molds.