Sure is a beautiful rock you have there @nat-expressions!
Are there little crystals in the holes? Searching the two images
at the top it came up with cookies lol one was peanut butter
the other choc chip, funny the searches.
Sometimes it will show something similar to what looking for.
I was going to say petrified potato! :-)

@goat-girlz mentioned sulphur, it does look volcanic
in color and perhaps the holes are from gas bubbles.