Board Thread:General Discussion/@comment-3571637-20150702052958/@comment-26445035-20150710110346

Guys, Rebecca Sugar confirmed on her Twitter that the sandwich is actually Sardonyx and Onion's half-gem son that just shape-shifted accidentally into a sandwich because her genetics are going haywire. Sardonyx didn't need to sacrifice her gem because she's actually a fusion of Connie and a sandwich, which is why her son was forcefully turned into a sandwich.

If you don't believe me, link to source, totally legit.