The suspension of the Federation terraforming project on Velara III after an engineer's death revealed an intelligent inorganic life form living in the planet's thin layer of saline water.
In The Next Generation episode Home Soil, the Enterprise-D calls at Velara III, where a small team under the abrasive Director Kurt Mandl is turning a supposedly lifeless world into a habitable one. During the visit the hydraulics engineer Arthur Malencon is killed by a laser drill that then attacks Data.
In the drilling tunnel the crew find a point of flashing light and bring it aboard. In the medical laboratory it grows, takes over the computer and speaks through the translator, calling humans ugly bags of mostly water and declaring war. The team's drilling was draining the salt water that links the tiny crystals into a thinking whole, and Mandl had ignored the signs.
The entity depends on light, so Picard has the laboratory darkened until it agrees to talk. It is returned home, and the planet is placed under quarantine.