Lava Lift

A Lava Lift or Skull Raft is a raft made out of bones and is the precursor to the Spine Coaster. It debuted in the game Super Mario World.

Super Mario World
In Super Mario World, Skull Rafts are used to help Mario and Luigi cross the lava river. They are only seen in Vanilla Dome 3 and Vanilla Dome 4, where there are large areas filled with lava rivers. However, sometimes, Blarggs will jump out and try to attack Mario or Luigi, so they must jump to avoid them, then land back on the Skull Raft.

Super Mario Maker / Super Mario Maker for Nintendo 3DS
Skull Rafts, now known as Lava Lifts, reappear in Super Mario Maker and Super Mario Maker for Nintendo 3DS. This appearance is different than in Super Mario World. They are able to move in air on top of moving in lava. They can be used in all four styles, featuring new sprites for Super Mario Bros. and Super Mario Bros. 3, and a 2.5D model for New Super Mario Bros. U. A blue, faster variant also exists, that will not fall off the screen after a couple seconds. The rafts are generally used to follow tracks.

Super Mario Maker 2
Lava Lifts return in Super Mario Maker 2, where the blue ones are now referred to as Fast Lava Lifts.

Super Mario World television series
In the Super Mario World television series, a Skull Raft appears in the episode, "Mama Luigi". Here, it shows that the Skull Raft is made of both wood and skulls, not just skulls like in the video game. During Luigi's story, Luigi got attacked by a Fire Sumo and fell into the Lava Pits. However, he landed on a Skull Raft, which saved his life. Unfortunately, he was heading for a lava waterfall, and Luigi and the Skull Raft fell down the waterfall, with Luigi landing on solid ground, where he found Baby Yoshi.