A parasitic life-form that obtains a new
host body by destroying the original and creating a copy.
An
X Parasite samples DNA data from previous hosts and can then change it's shape accordingly.
X Parasites have been known to copy the actions of the hosts so perfectly that often there are X Parasites walking in the streets of you local city and nobody even realises it.
The X Parasite, if threatened, will destroy a life-form and
steal it's DNA.