You have discovered a scavenge coin! PM me this link in order to attempt to claim it. Only the first to do so will earn the point. You will not know if you are the first to claim it until the challenge is over.
If you have found a scavenge magnet, you can claim this using the magnet (still through PMs) and bypass the first-come, first-serve rule. Potentially steal the coin from whoever may have found it first. If you are the first to claim it while using the magnet, you will have only wasted the magnet.