I expected Silurian come from silicon but I was wrong. Once heard the idea that there might have been silicon based life on earth and all the sand we have is fr

I expected Silurian come from silicon but I was wrong. Once heard the idea that there might have been silicon based life on earth and all the sand we have is from that period - much like oil is dead carbon based life. Scientifically there is not much to it, I think, but it would make a good basis for a SciFi story nevertheless.