Maria is a name, of course, but it's also the plural of mare, which is one of the grey splotches you see when you look at the moon.
This sort of maria is pronounced MAReea: so that makes three pronunciations for this word - m'REEa or m'RAIa for the name, and MAReea for the marks on the moon.
Maria were made by huge volcanoes. Massive amounts of lava exploded out of these moon volcanoes and spread out into enormous dark pools. When the lava cooled down it went solid and turned into a rock called basalt.
People have been wondering about maria for a long time. There was the green cheese theory, of course, and people also thought for a long time that they were seas, which was how maria got their name: maria means seas in Latin.
Each sea has its own name. There's the Mare Imbrium (Sea of Showers) and the Mare Humorum (Sea of Moisture). The Mare Humorum is easy to spot because it's the dark spodge nearest to the bottom of the moon.
These two maria are rather badly named, though, because none of the maria ever get so much as a sniff of a shower, or in fact ever get moist at all.
Spot the frippet: maria. From the Latin word for seas, as I said.
Do look, and be amazed
The frozen moon
With spouts of fire.