Identify these deposits

[Griffin_pak]

Saltwater pool. These have been here since the start. Some above water and some under water.
Very hard. One seems to have broken though a small crack in the blue tile underwater.


Any idea? Or just calcium. Size is same as 5 years ago, should I take a screw driver to them?

 

[BDY]

Put some in a container and pour vinegar on it. If it fizzles its likely calcium