Nanovore
From Tardis Wiki, the free Doctor Who reference
Nanovores are microscopic robots, probably similar to to nanoforms(SJA:Prisoner of the Judoon) and nanogenes(DW:The Empty Child/The Doctor Dances). At some point they attack The Doctor and Donna Noble on floor 139 of the edifice(DW:The Forever Trap). They are, apparently, capable of "eating" absolutely anything.