Phantom craters are craters that have lost their characteristic shape, meaning a deep hole with high walls and often prominent central peaks. They are much more subtle, often difficult to recognize like the ghost I described in 2012.
In this photo we have two easily visible ghosts, they are, Wallace, in which the southeast walls are missing, and Stadius, already in a much more advanced stage of degradation, both indicated in the photo.
The right time to observe this class of craters is when they are close to the terminator, as at this moment, even small elevations and depressions in the ground are easily evident.
A ghost crater is a crater buried in lava, with only the crater rim visible or sometimes not even that.
How are they formed? Let's say a regular crater forms from an asteroid/meteor impact at some point. Thereafter, during the period of active volcanism on the Moon, lava eruptions in the area may fill the crater to the rim, leaving only the rim behind.
Many of these phantom craters were located on the moon, including the one I posted a new topic on Astrobin recently:
https://www.astrobin.com/0fkqmh/, as well as was described in the book "Astrofotografia Amadora no Brasil, chap. 19, page 282".
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