So, we know that a metamorphic rock is either an igneous or a sedimentary rock that are exposed to intense heat and pressure.
But when the metamorphic rock is thrusted deep underground through subduction, it will again be subjected to intense heat. This can cause it to melt, turning it into a magma. When the magma cools down, it again becomes an igneous rock and the rock cycle continues.
See attached image for most common formula of sulfuric acid.
I am thinking it is by heating themselves in sunlight. I think this because when I bring lizards to mind, they are cold blooded, and they need sunlight to bath in so they do not start to lack warmth to live.
I hope this helps.
1. Growth
2. Tumor
3. Body