Doomsday device

A doomsday device is a planet destroying interstellar automaton first encountered by Commodore Matthew Decker in the late 23rd century. Captain James Kirk and the crew of the Enterprise worked with Commodore Decker to develop the Kirk Defense, which is now standard Federation strategy when dealing with these devices. The devices themselves are virtually indestructible, being made almost entirely of neutronium, and capable of sustaining themselves indefinitely via full-conversion furnace.