Giant Amoeba

The Giant Amoeba was the final creature spawned by the Genus, created as a result of large amounts of napalm being exposed to the aliens, triggering an evolutionary response that manifests itself in this form.

It basically functions similar to a normal amoeba, except it is not known how it feeds, but it is known that it undergoes mitosis (possibly leading to another evolutionary path) and it has an orifice underneath it. As a nitrogen-based life form, it can be poisoned by selenium.