Is this bowls potter or history known to anyone please

Hi
I have a 8" wide by 4" tall bowl that has lots of small bumps in it under the glaze.

cannot find any mark but could be one hiding somewhere

Is it tenmoku glaze?

Any idea of the date range or potter?

The bumps appear to be either bubbles in the glaze, or grogg in the clay, or a combination of both. Possibly a brown ash glaze that the potter has made themselves. Different wood and plant ashes gives different coloured glazes, which some potters like playing with. Possibly a test piece.