Unless it was microscopic. Microscopic invaders were more of the threat 
nowadays. Just to name one example, there was Red Death, a.k.a. the Seven 
Minute Special, a tiny aerodynamic capsule that burst open after impact and 
released a thousand or so corpuscle-size bodies, known colloquially as 
cookie-cutters, into the victim's bloodstream. It took about seven minutes for 
all of the blood in a typical person's body to recirculate, so after this 
interval the
cookie-cutters would be randomly distributed throughout the victim's organs and 
limbs.