C-C-O is a 3 piece burr puzzle. Two are shaped like a "C" and the third like an "O". It will come assembled in the knot like object seen in the main photo. Your goal is to first get the pieces apart, and then get them back together. This is one of the simple looking puzzles that turns out to be not so simple.... 5 to 10 minutes would be a normal solution time, but its a fun challenge that most people will want to tackle.