Thats unusual, and unusually nice. In that top pic, is that what appears to be scratchings in the hollowed area ?

Finally you have an ancient artifact that is perfectly current in the 21st century. . .
For the kitchen sink, a soap dish [ stone ]

Those are scratchings,very,very smooth also.Even though its used very heavly,im calling it un-finished.I like to see notches or holes in my boatstone.....

The term Boatstone did not originate in Texas, but

the central midwest and northeastern U.S. Most boat-

stones do have holes and notches, as they were worn

as body & dress decor, and some utility uses. Our word

for essentially the same thing here is Gorget.