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.
 
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