Capsule
From Sonic Retro
At the end of every Act 2 in Sonic 1, Sonic 2, Sonic 3 & Knuckles and Sonic Advance 1, a capsule is placed containing animals which you free and end the level by jumping on the button at the top of the capsule.
At the end of every Act 2 in Sonic 1, Sonic 2, Sonic 3 & Knuckles and Sonic Advance 1, a capsule is placed containing animals which you free and end the level by jumping on the button at the top of the capsule.