I found three on the mountain at 80 lat 70 lon on lost island. They just look like yellower rocks when in rock form. If you are unsure look at them with spyglass. After I found a high level I ran away and set up a trap. After trapping it and placing a canon I put doorways vertical up like 6 times infront of my canon to prevent the rocks from breaking the canon.
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 .