Japan's Kaguya (Selene) orbiter first found three pit craters, each the diameter of three football fields end-to-end. The LRO team has added 10 candidate craters - one, ironically enough, in the Sea of Tranquility. (Tranquility Place here, vacationers welcomed!)
The team is planning to acquire stereo images of both large and smaller lava tube skylights now being discovered. The detailed topographic images will better confirm the origin of these unusual features.
Photo credits (from top): NASA artwork, lunar "skylight" by NASA.