>They conclude that the mantle transition zone--410 to 660 km below the Earth's surface--acts as a large reservoir of water.
Sadly there will be no eyeless space whales in our basement, given that the temperature at that depth on Earth is around 2,000° Celsius.
eyeless FIRE whales
I like this line of thinking way better lol
That sounds like water in hydrated minerals rather than liquid water? In terms of settling inner solar system asteroids where the sun bakes everything you're looking for material with as much easily extractable water as concrete to make a comfortable home.