A hand-held digging implement used by the Troglyte miners of Ardana to extract zenite, which also serves as an improvised weapon for the Disruptors and in Kirk's confrontation with Plasus.
The mortae is the basic mining tool of the Troglytes, the labouring class of the planet Ardana, who use it to dig zenite out of the mines beneath the cloud city of Stratos. It appears in the original series episode The Cloud Minders.
The tool doubles as a weapon. The Troglyte leader Vanna carries one when she steals into Kirk's quarters on Stratos and attacks him as he rests, and the Disruptors are armed with them on the surface.
Later Kirk has the High Advisor Plasus beamed into a sealed mine chamber and orders him to dig with a mortae, to prove that unrefined zenite gas dulls the mind and inflames the temper. Under the gas the two men end up fighting each other with the tools.