Kreetassan glowing lichen

The 'Kreetassan glowing lichen was a plant species, a lichen native to Kreetassa. 

History
When a living mirror duplicated Doctor Beverly Crusher and Lieutenant Worf of the Federation starship USS Enterprise (NCC-1701-D) during a routine planetary survey in the 2360s, Lieutenant Commander Data speculated the cause might be an automatic biological function. Data compared based his hypothesis on the glowing lichen of Kreetassa.