This drain was under the supply faucet for the “tub”. Some jokester remodeled his bathroom. The shower and bathtub faucets, when turned on, pour onto an extended tile shelf and then onto the floor. This drain is under and to the right of the faucets on the vertical wall. Note: it is not on the floor of the tub. What could this be for?
Half-A$$ over-flow.
Oh yeah. Oops. I actually posted the wrong picture. I guess I don’t have one of the “thing” in question. It was actually next to the overflow and looked like a water connection without a knob. It was below the other fixtures. If you can see the ledge just above the overflow in this picture, that is where the water from the faucet pours onto. Great Job Buddy! This is from a home that a realtor tried to fix on his own and sell at above market price. The summary report was three pages long.