The Lunar Reconnaissance Orbiter, LRO, has taken images of a chasm on the Moon. Believed to be a partially collapsed lava tube, the gaping hole has a partially illuminated floor carpeted with boulders. This is a bit of a surprise if true, however, as there were not thought to be many lava tubes crossing Mare Ingenii, the Sea of Cleverness, where the images show this feature lies.
Meanwhile, a citizen science project, the Mars Student Imaging Program, was happilly allowing pupils to study the phenomenon of lava tubes on Mars when they saw a similar thing. Another hole in one of our pristine planets. They were studying the area in thermal emissions and were able to spot the feature through the characteristic profile of such a pit. During the day, the shadowy depths are colder than the surrounding area and during the night, the blanketed tube breathes out warmer air through the pit.