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In the science fiction television series Stargate SG-1, Crystal Tunnels are used by the Tok'ra to quickly build a base and associated structures. These underground tunnels are an effective way of hiding from the Goa'uld, because of their underground nature, and also due to the fact that the Tok'ra usually construct a base on barren planets, which have no life, and thus a way to deflect attention to a possible Tok'ra presence.

These crystal tunnels have no built in ventilation systems, but produce oxygen from chemical reactions with certain types of rock that they construct their tunnels through, a byproduct of the growing process. There is often enough oxygen produced to allow the Tok'ra to install more permanent life support systems. These tunnels can also be quickly collapsed and destroyed if necessary, for instance if it is necessary to retreat if the base has been detected. The tunnels don't typically have an entrance or exit shaft to the surface, but instead use transport rings. There may or may not be more than one transport ring system in a possible Tok'ra base. Goa'uld Al'kesh bombers are capable of collapsing and destroying these tunnels by bombing the surface above a tunnel.