Snake Blocks are blocks that start out as a normal platform but will move when they are stepped on by either Mario or Luigi. They would first appear in Super Mario World. They would look like Used Blocks that appear in Super Mario World, but be green in New Super Mario Bros. They would track across the screen, turning in every direction as they follow a pre-determined course over obstacles like pools of lava. If Mario or Luigi fall off, then they will continue to move.
They would appear in the Boo Moon Galaxy, Bowser's Lava Lair, and Bowser's Galaxy Generator in Super Mario Galaxy 2. They would be pink in this game and this would mark their first 3-D appearance. They would be four blocks wide, instead of only showing one like they did in previous games.