When knocking out a high level rock elemental, make sure the last shot is aimed from the side. When shooting straight into its head, the cannon ball goes through its head and deals extra damage to its body which will start the taming effectiveness 90% instead of 100% if it isn't done from the side on the last shot.
It's a bit silly that kibble tames it a lot better than rocks or sulfur because even in the dossier it says that it lives off of absorbing nearby rocks and minerals. So mabey they should make it so you have to feed them a rare mineral like obsidian what if they made it so you could tame one fast and with high effectiveness by giving one a few hundred or few thousand obsidian . or what if there kibble was made out of a combination of ores and minerals .
I think there should be a metal golem which is stronger and harder to tame. Maybe it could collect metal only and more effectively than anything else. ps. It’s just some idea I came up with in my spare time