My uniquely glazed Serving Bowl with 5 Smaller Bowls

I have had these dishes, since I found them several years ago at a local thrift store because I loved the unique design in the glazing of the pieces. I've not found anything like them in my occasional attempts to research them, since they have no markings to make researching them easier. It's interesting to me that each dish has a similar "blemish" in the glaze underneath each dish, which makes me wonder if there was possibly something attached to the dish while being worked/fired and then removed. The serving bowl is almost 10" wide and 2" deep, while the small bowls are 5" wide and 1" deep. I suspect they're porcelain, but not 100% sure of that.
Can anyone tell me more about these dishes? Where they may have been made, or anything else that I could search on? Appreciate any help. Thanks in advance.