In 2360, after a Federation reconnaissance expedition certified the planet was lifeless, its Terraform Command established the Velara Base on Velara III. This base was responsible for a multidecade terraforming project with the aim of establishing a M class environment on this planet.
The terraforming was, however, canceled in 2364, when it was discovered that the process was killing silicon-based lifeforms, dubbed as "Microbrains", in a thin layer of water between a sandy surface layer, or topsoil, and a layer of rock.
Following the discovery of the "Microbrains", and the retaliatory death of hydraulics specialist Arthur Malencon by these lifeforms, an agreement between the little crystals and Captain Picard of the USS Enterprise-D placed Velara III under an indefinite quarantine with the hope of restoring communications with the microbrains in 300 years. (TNG: "Home Soil")