SUPER emeralds
In
Sonic 3 & Knuckles (Sonic 3 and Sonic & Knuckles together), you could get the 7 Chaos Emeralds just like in another Sonic game. But in
Mushroom Hill Zone, you could teleport to Hidden Palace Zone and upgrade the Chaos Emeralds to Super Emeralds. This means that you could transform into your character's Hyper form = t3h
pwn4g3!