I did little more digging (the net) and found references to to prehistoric volcano effigy incense burners discovered in Mexico. They were made out of pottery however rather than stone. I also found some stone effigy incense burners with holes not much larger than the hole in your pictures. Incense burners documented in Ohio Hopewell sites seems to me to make that a[emoji6] reasonable consideration. I'm not suggesting , nor have I suggested "what it is" only what it possibly could be. I'm not saying "no" to anything, just trying to think with an open mind, but not so open that my brain falls out.[emoji6]