User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-5460283-20120913130341/@comment-5043481-20120914162615

Well, since you may need a different solvent for silicon based life forms, you would at least not be able to digest it, and it would be likely that some of the dissolved compounds would be toxic.

And also, I think the reason that none exist on earth is that carbon is simply a better element for life.

One of the main problems with silicon based life forms is that silicon dioxide (which would be a product of respiration with oxygen) is an insolouable solid, sand. This ceases to be a problem at the melting point of silicon dioxide, which is 800 to 1000 degrees C. This is molten rock temperature, so I could be that gravios has molten sand for blood.

Personally I think it is a nice idea but a bit of a long shot. I think it is more likely that they simple eat rock to make their shells. (thier blood and muscle layers are red, like in most other animals.)