A Romulan mine
Damage caused by a Romulan mine.
A Romulan mine was a spatial mine equipped with a cloaking device. A single mine's explosive yield could cause significant damage to Earth Starfleet starships of the mid-22nd century.
The Enterprise NX struck one such mine while in orbit over a Class M planet. The mine destroyed several compartments on the port side of the starship. Another mine landed on the hull but failed to detonate. Lieutenant Malcolm Reed and Captain Jonathan Archer were able to disable it. (ENT: "Minefield")