h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I think somewhere it has been established that whilst they assimilate everything, they decide what elements are useful to be retained. Otherwise the human concept of individualism would have infected them long before I,Borg. It would appear that only an already assimilated Borg shares totally with the collective - it therefore follows that there is a degree of filtering when assimilating new species. That begs the question: what is the most useless species the Borg have assimilated? For that matter is there a species so imperfect that the Borg didn't bother to assimilate them?

When taking over planets they probably cleanse it of all the amoeba, plant life etc. before assimilating anything showing intelligence.

..but that would destroy the ecology of the planet - do the Borg need anything natural at all?

Remember First Contact.........all life was Borg. Also remember they could quite easily live on Mercury or Pluto - they don't even need an atmosphere. And where's their ecology?

The borg take elements from all cultures, taking their technology and cloning new borg with all the best bits of each species(which they CAN do, which raises the question, why assimilate a WHOLE species, and not just the best examples of the species) hence "WE WILL ADD YOUR BIOLOGICAL AND TECHNOLOGIACAL DISTINCTIVENESS TO OUR OWN". They DO need an atmosphere (First Contact describes the EXACT atmosphere, actually) and when they assimilate a planet, they leave it stripped clean, of people, animals and minerals.