I personally believe Sardonyx is a fusion of Japser and Peridot. Sardonyx seems to have the same colour scheme as Jasper. As we have seen in Steven Bomb 2.0 Malachite has became unstable. I think Jasper will escape and try to find Peridot, and fuse. Also Sardonyx is the alternative birthstone for the month of August, Peridot is also a birthstone for the month of August. Conicidence? I think not.
Take this with a grain of salt, I doubt I'm correct but that is what I think.
Has a nice day y'all Peace -Wolfy