Scientists have discovered that bacterial parasites can deposit their genome into the genome of their host species. The presence of this sort of, well, I'm not even sure it's an attack, but at any rate this sort of thing is quite likely to be much more widespread than what's been discovered so far. All those samples geneticists have been tossing away as contaminated may in fact represent a part of the animal's genetic makeup.

Just when you thought biology couldn't get any weirder...