Silicon-based lifeform

A silicon-based lifeform is a corporeal lifeform that uses silicon as the basis of its structure and life functions rather than carbon. Silicon-based lifeforms generally do not evolve on M class planets. 

In 2151, Captain Jonathan Archer of tried to convince Commander Charles Tucker III that Starfleet had sent them to a planet to meet with a silicon-based lifeform, when Tucker was hallucinating "people coming out of the rock face." 

Silicon-based life was thought to be physiologically impossible before the discovery of the Horta of Janus VI in 2267. It is not possible for silicon life to evolve in an oxygen atmosphere. 

In 2269, the USS Enterprise (NCC-1701) encountered Yarnek, a representative of the the Excalbians, a shapeshifting silicon-based species native to the planet Excalbia, described as being "almost mineral" and "like living rock with heavy fore-claws." 

In 2336, the Omicron Theta colony was destroyed by the Crystalline Entity. 

In 2364, the USS Enterprise (NCC-1701-D) discovered the microbrain, an inorganic lifeform found during terraforming of the planet Velara III.

In 2374, a Hirogen hunter boasted to Tom Paris about tracking a silicon-based lifeform through the neutronium mantle of a collapsed star. 

Silicon-based lifeforms

 * Crystalline Entity
 * Excalbians of Excalbia
 * Horta of Janus VI
 * Microbrain of Velara III
 * Silicon-based parasite
 * Silicon-based virus