Big Purple Space Amoeba
The Big Purple Space Amoeba (BPSA) is the mysterious entity whose cells power the X-14 Tantalus rays on the Vorticon Mothership. Little is known about it except that, unlike true amoebas, the BPSA consists of many cells, perhaps placing it in a similar category to Volvox and other primitive multicelled animals.
The only time it (or part of it) is seen in the Keen series is in the Tantalus rays themselves, where solitary cells can be seen powering the rays. They are the only part of the ray that is vulnerable to attack and can be destroyed with spectacular results.
The fact that single cells can be utilized to power a ray of planet destroying capability suggests that the complete amoeba is of unprecedented power. The fact that it is always referred to in the singular article ("the" BPSA) indicates that it is unique, one of a kind and thus severely endangered. Sadly, it appears that the Grand Intellect knows the location of this specimen and may use it again to devastating effect.