New Variant For Magma Block

I was playing Minecraft and when I was in the ocean I noticed a magma block and it was ok but I started to think that something was wrong because magma block has netherrack in it and netherrack is something like hellstone so it came to my mind to add a new variant of magma block which would cause there to be two types of magma blocks which would probably be called: netherrack magma block and cobblestone magma block, and cobblestone would be called that because all parts of netherrack would turn into pieces of cobblestone