Rima Hyginus

The rille is a graben opened above a dike, a sheet of magma forced upward through the crust. As the dike drained or the magma withdrew, the ground above it collapsed along two faults, and where the collapse went furthest it left pits rather than a trough.

Those pits are the test. The craters strung along Rima Hyginus have no raised rims and no ejecta, which no impact of that size could manage; they are holes into a void beneath. Hyginus itself, at the junction of the two branches, is the largest of them and one of the few craters on the Moon that is not an impact structure at all.