The Singularity Scalpel is an alien medical device for operating on a body without opening the patient. Torchwood found it but was unable to use it properly at first but Owen Harper managed to use it to kill a Mayfly which had been implanted into Martha Jones. (TW: Reset)
It was used again to remove a shape-shifter's egg from Gwen by Rhys, although it had been modified by Owen. (TW: Something Borrowed)
