The Spike Block is a pink cube-shaped Container with orange-pink metal frames and the Pink Spikes' symbol on the front.
The Spike Blocks only appear in Planet Wisp. In gameplay, they serve as obstacles blocking the player's path. They are unmovable and virtually indestructible, meaning none of the player's regular moves can destroy it. The only means of destroying them is by using the Pink Spikes which lets the player break them apart upon touch.
↑BradyGames (1 November 2011). Sonic Generations: BradyGames Official Strategy Guide. BradyGames. p. 170. ISBN 978-0761555100.