This is a 50 ft crag located just upstream from the Dome, Frogman's Pinnacle, Ament's Rock near the mouth of Boulder Canyon. Nice name...now there were 3 of us there...hey..... Obscure, short, but uncrowded. It is listed in both Rossiter's guides for Boulder Canyon with a single, oddly named route, Anus Great, a 4-inch crack. At least 2 other lines have been done here.
Park at either of the lots at the mouth of Boulder Canyon, as for The Dome or Elephant Rocks. Cross the bridge, follow the trail about 200m upstream past a fenced part to a sign indicating the border of Boulder. Look uphill & identify a short, wider-looking crack. Hike up a loose path about 75m to the base. Beware of poison ivy, especially at the base of the right side of the crag.
I lost a BD ATC-Guide two weeks ago or so up in Boulder Canyon. I think I lost it around the Dome/Elephant Butresses area (but could be somewhere else). I'm just a poor college kid with no money and now no belay device. If you found it and returned it, I would be extremely grateful and would be more than happy to reward you with some beer.