Transit of Deimos from Mars
A transit of Deimos across the Sun as seen from Mars occurs when Deimos passes directly between the Sun and a point on the surface of Mars, obscuring a small part of the Sun's disc for an observer on Mars. During a transit, Deimos can be seen from Mars as a small dark spot rapidly moving across the Sun's face.
Source: Wikipedia — Transit of Deimos from Mars (CC BY-SA 4.0)