Perhaps not, if they originated here. They may find conditions elsewhere more conducive to their existance though and they could be "preparing" Earth for their arrival/return, en masse, to harvest said silica/silicon? There's also a tidbit somewhere, not sure it was OP, about Opals... if it's all connected I would be absolutely astounded but the stimulating conjecture certainly conjures up much 'food for thought', especially if you are an SBLF.

The graphite/carbon theories floating around may well be relevant too ~ this silicon theory could be miles off ~ there may also be many parallels possible ~ at some higher vibrational/atomic rate perhaps...

I would much rather deal with 'stuff' I know exists, from an intellectual sense, but 'living on the edge' has plenty of appeal too!

Ciao!