Infinitely reviving boss ad in Fortress

Bug Report ID: #3927160503

I've killed the boss, but one of the coins on the ground remained after and started reviving as the "Spirit of Pirasha" monster. Killing it just spawns the coin back on the ground again, after which it waits a few seconds and revives.

There were a lot of coins on the ground when the boss died, I guess one didn't get removed properly.