Turtle Shell is the third stage of the 2-player Battle mini-game in Sonic Heroes. Like with the other dedicated stages, players compete to force each other off the stage.
Set atop the giant sea turtles seen in Ocean Palace, this stage is a long, rectangle-shaped arena with twelve Rings laid out in the middle of the arena and two Wide Springs placed at both ends. Lighting up all three lights on either of the Wide Springs will award a Team Blast Ring, allowing instant use of a Team Blast.
Item Balloons will frequently fly across the arena, each of them containing various power-ups like a Shield, Invincibility or Power Cores. Unlike the other Battle stages, only one Power Core is given to a player from these Balloons.