Singularity scalpel

The Singularity Scalpel was an alien medical device, believed to be used for operating on a body without opening the patient. It was discovered by Torchwood 3, but they were unable to use it properly at first. After practice, Owen Harper managed to use it to kill a Mayfly which had been implanted into Martha Jones. Prior to this, he killed a man with it when it blew open his stomach while he was attempting to eradicate a Mayfly. (TW: Reset)

It was used again to remove a Nostrovite egg from Gwen Cooper by Rhys on their wedding day, although it had been modified by Owen. (TW: Something Borrowed)