Need a special tool!

[sevver]

You can also maybe use a 12 point socket. Or if you can find one, a square socket, they make them, my Dad has some. Then you could use a ratchet. Otherwise, we used to use Valve Keys to turn undergound valves, you could have one of those made up. Basically the same principal as the basin wrench, except there is a square deal on the bottom.

Oh, and if it is like a cleanout cover or something, most plumbers would just bust it out and replace it with a new one. lol.