I received this from my uncle, who was an antique dealer. It's a suzuri (inkstone) in a wooden box. It's adorned with a dragon carving. I was told at the time that it was unusual to have a place to hold water, in addition to the part for grinding the ink. The wooden box is 17cm wide, 18cm long, and 6cm high. The inkstone itself is 15.5cm wide, 15.5cm long, and 3cm high.