Singularity scalpel

The Singularity Scalpel is an alien medical device, believed to be used for

operating on a body without opening the patient. It was discovered by Torchwood 3 but 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 as 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 by Rhys on their wedding day, although it had been modified by Owen. (TW: Something Borrowed)