Mare Anguis (the "serpent sea") is a
lunar mare located on the near side of the
Moon, about 150 miles in diameter. Located within the
Crisium basin, Mare Anguis is a part of the
Nectarian System[?], meaning that it was formed during the
Nectarian[?] time period. Like most mare, the surface of Mare Anguis is dark, indicating that it has been filled with volcanic
basalt.