The moniker is the name of any creature's genome file. In Creatures and Creatures 2 this was a 4 character alphanumeric string - automatically allocated monikers were in the format numberletterletterletter, eg. "1VWY", but monikers like "lucy" or "eve_" were also valid. Importing two creatures with the same moniker can cause the game to crash, which is why it is not a good idea to try to export a creature and then import it twice.