Regis III, type sub-delta-92, constellation Lyre

"The evolution of life on Regis III must have been going on for approximately several hundred million years. They had also discovered considerable amounts of green algae; this should account for the presence of the oxygen in the atmosphere. (...) However, one organ had been found in the fish specimen for which no corresponding terrestrial structure was known to the examining biologists. This seemed to be a special organ of sense that reacted strongly to minute variations in a magnetic field." - The Invincible by Stanisław Lem