Nullswarm

The Nullswarm are a parasitic hivemind of miniscule insects, each too small to be made out by the eye.

Upon finding their prey, a group of Nullswarm immediately take control of it, mimicking it's movements and actions perfectly, down to even a personality. In the meantime, a portion of the group begin consuming anything considered unneeded in the mimicking of the being they take control of; generally moving from fats and other reserves to slightly more important components like muscle until the portion is fully sated. Following this, that portion of the Nullswarm proceeds to breed, doubling it's number, and then leaves the Victim - quickly resuming it's hunt. With this process taking anywhere from an hour to several days depending on the size of the victim, this process can lead to the fast infection of a settlement.

Following finding a host, the Nullswarm can survive roughly 5 weeks, with the realistic mimicry breaking down after four weeks when the Nullswarm which stayed in the victim begins running out of food and eats the remains of the victim. The victim loses tissue in order of importance, usually staying roughly identifiable until two days before the hive starves when the Nullswarm begins feeding on hard tissue including: bones, cartilage and exoskeletons.

The Nullswarm were largely responsible for the failure of all human excursion attempts to the Vannor Sporewoods which plays host to a permanent nest of Nullswarm.