Barzan II

Barzan II was an independent Alpha Quadrant world populated by the Barzan people. This non-Class M planet from orbit had a green color and an extremely thick cloud cover. Most other species could not tolerate the Barzan atmosphere and breathing devices were needed for Barzan people leaving the world. 

In 2366, a wormhole was discovered near the planet leading the Barzans to negotiate access with various Alpha Quadrant powers. A short while later, it was determined that the wormhole was unstable and thus lead to the negotiations falling apart.