Maybe the reference is to an aquifer.
Yes. That is why some rivers have rapids. Water going over rocks create them.
Because they fall in the water over time
Newts don't specifically hide under rocks but they go under rocks whenever they want too. Rocks are in the water and on land and newts are totally aquatic and specifically aquatic so they can go under rocks when they feel like it.
sedimentary
NO of course not. They are from lava.
Permeable or porous rocks
volcanos under water exploded and rocks formed it.
under bodies of water
yes
under depths of water
Grainy rocks not only absorbs water better than crystal rocks, but it filters the water as well.
The Study Of The Surface Or Rocks Or Everything Under Water