Not sure what you're looking at exactly in this one.
If it were a tunnel and underground, you wouldn't see it. This is a
Rille and it also looks like the
one that Apollo 15 landed next to.
Or perhaps just a boulder having rolled down the side of a hill.
The Lunar Orbiter probes used film to take photos. This meant that the film had to be developed and scanned and then transmitted all within the probe.
I believe these markings are from the development process.