Tyrrhenus Mons (Mars)

This feature is named after an earlier feature.

The name "Tyrrhena Patera" now refers only to the central depression, a volcanic crater or caldera. Pit chains are found at the summit. They are formed by collapse of material into underground voids. (wikipedia entry)

A mons is a mountain. On Mars they are named after the nearest named albedo feature on the Schiaparelli or Antoniadi maps.