Ok, first of all the general shape looks good. Proportions of all the elements are fine, too. Apart from the symmetry you mentioned, the head needs some more work. The best reference for further detailing (and also texturing) would be the "acid tube" (the codename doesn't quite fit it anymore, it's more of a "gas flower" now).
Here's the low poly version with normal, specular and glow map (the latter for the eyes) applied:
As you can see, the six eyes are only part of a face, so feel free to add more defining elements such as teeth to your model. For a start it might be wise to simply copy the face of the acid tube, as both species are obviously close relatives. (Both of them emit vapors from their pores, the acid tube to repel intruders and the booster to heal teammates.)
You can imagine alien structures to be former creatures that evolved into immobile forms. Their feet turned into hooks or similiar limbs that allow them to stick to surfaces (in some cases even to wall and ceiling, although the booster will most likely stay on the ground) but they still have a face and sometimes arms that will idle and show pain reactions when hit.
Note that the acid tube is really symmetrical but it doesn't quite look like it. However, due to the flat shape of the booster you might want to go with an actual assymetric version.