Air nailer projectiles
Essentially one legged staples, the bottom section is grooved which is why it is so hard to get them out.
The best removal tool I have found so far is a set of Vise-Grips. Unlike nail pulling pliers, you can put a lot more pressure on without cutting through the stem. The rounded top section of the tool can be abused to provide the same action as nail puller pliers and because the diameter is larger (assuming a regular size set), you can pull longer before having to reset your grip.
If they are too close to the floor for the tool to catch, you can drive them below surface level with a nail set. These things are hardened. Drilling will likely do a bigger number on the floor as the bits will skip.
