I’ve found the eggs. The eggs are located inside the volcano in an amethyst cave. There are lava pools with groups of magmasaurs in them. There are small islands with craters in them, within those craters the eggs are nestled within. But be careful there are lots of magmasaurs, magma, and what look like varient rock elementals.
Magmasaur is able to destroy ALL STRUCTURES utilizing its searing spit. While it is a walking forge it produces metal at the same rate as a refining forge. You can use the jump button to taunt other creatures and when holding searing spit use crouch to erupt. (This attack pushes creatures back and leaves magma everywhere) it is breedable in lava. Hope this helped
Magmasaurs are phenomenal metal.and stone gatherers, but also really good crystal and obsidian gatherers too. Doesn't seem to be mentioned often. They can gather oil from oil rocks as well, but cannot gather ambergris or element shards.