Rock

The Rock is an item which transforms GE into Volcanic Energy, which can then be turned into Volcanic GER. This only changes the looks, and is not advised to be used as volcanic ger CANNOT be upgraded to GER OH, so you should keep regular GE, turn it into GER, than GER OH.

You also can't get Universal GER with volcanic GE, so its best advised to stay as regular GE until you get an upgrade item.

Volcanic GE/GER provides no advantages over normal GE/GER users, its simply a rarer reskin, as is with most stands like that.

You can also change King Crimson into King Crimson Magma with the rock. King Crimson Magma is just a reskin of the regular KC, with no advantages. BUT if you use the rock on KC to make KCM, you will not be able to upgrade to King Crimson Requiem.