Pit check
Miners have, for centuries, been placing these control plates — pit checks — on the control boards. Each team working together in the mine has its own board, and in this manner, which is also the most straightforward, we always know how many miners are present. Upon completion of the shift, each miner removes their pit check; any pit check remaining on the control board signifies that the miner is missing or, in the worst case, has been involved in an accident.
The pit check is said to bring good fortune and can therefore also be associated with the miners’ greeting.
Good luck!