Another interesting hit on the Sciencebase site today: “why silicon is a good alternative to carbon to base a life form on”. Outside Star Trek and Doctor Who, I didn’t think it was. Silicon doesn’t concatenate (form chains of atoms) to quite the same extent as carbon or in the same way and so isn’t able to form anything like the wide array of molecules on which carbon is based (millions of them from simple hyddrocarbons to proteins and DNA).
Saying that, if a computer could evolve from a grain of sand, then perhaps that might be considered a silicon-based life form Meanwhile, support your local “cobbles” clinic.