Assimilating races

Assimilating race denotes any alien species that has the ability to absorb genetic material from other organisms in order to maintain their species and invade others.

Methods of Assimilation
Different alien creatures often have different methods of assimilating other species:

Injection
This method has been used by a few species such as the Borg and Necromorphs to increase their numbers; this method is preformed when a member of a species injects their DNA or nanoprobes to take over and alter their cellular structure and eventually their minds.

Absorption
Absorption is often used by races to sustain their existence. Species that have this ability are usually amorphous, the amount of living organisms they absorb allows them to grow to monstrous size depending how much they consume. This includes The Thing.

Parasitism
An ingenious method which allows a species to take over the bodies of others and in rare cases mutate the DNA of their hosts, this includes the Yeerks, Brain Slugs, and Xenocytes, not to mention the most famous of all, the Pod People.

Reconstruction
This method is often used by inorganic life forms that can convert any living thing into whatever the life forms needs, such as the Geth from Mass Effect, which converts dead bodies into mechanical husks.