Carved Stone Dish

I am thinking maybe with Asian origin, probably recent? But it is not the typical stone I am used to see on Asian carvings.
It is about 5" x 4" x 1/2". There is one notch on the rim. Maybe an ashtray. Or small brush washer?

Thanks

 

I can see an artist using this with those long brushes, the type they use to produce paintings of Bamboo. I love those.

 

I see an ashtray...without much use.