The broad dark-floored crater is Endymion. At 76 miles wide, Endymion is a near clone of ever popular Plato. However, Endymion's location on the northeastern limb of the Moon places it away from most observer's attention. Endymion is pre-Nectarian, which means it is one of the oldest of lunar craters. Back during the Moon's volcanic era, magma seeped up through cracks in Endymion's floor and flooded the crater from the inside. In the more modern era (last billion years), light dusty streaks of ray material have deposited across the dark floor. I do not know the exact source of these ray streaks, but my bet is they came from Thales, a 19-milke wide Copernican Epoch crater about 150 miles north of Endymion.