Amniotic fluid

Amniotic fluid was a liquid which "life [came] from". There was some on Earth in the Atlantic. (TV: City of Death)

When Scaroth (a Jagaroth) tried to take off from the Atlantic in his Jagaroth ship, it broke and created a spark, reacting with the fluid, creating life on Earth. (TV: City of Death)

The Moon also had amniotic fluid, because inside the Moon, there was a creature, waiting to hatch. (TV: Kill the Moon)