I haven't seen any stone tools with perpendicular sides. In fact, I don't know of any other 90-degree stonework until the T-stones at Gobekle Tepe. If you cou

I haven't seen any stone tools with perpendicular sides. In fact, I don't know of any other 90-degree stonework until the T-stones at Gobekle Tepe. If you could point me to some examples I'd be very much interested in knowing about them.