nprofile1qy2hwumn8ghj7un9d3shjtnyd968gmewwp6kyqpq0nrcdm04dad32c0x4kuc9uwpff65rm8tnltr35j4yy775xh84jgs2g4ynj (nprofile…4ynj) I'd imagine they can probably handle a bit more torque without stripping the faces?
I see square nuts used on a lot of old-timey things too. Less nowadays. I've forged some square bolt heads out of hexagonal ones, for artistic reasons.