From the Super Mario Wiki
A Flatbed Ferry is a kind of moving platform which appears in Super Mario World 2: Yoshi's Island, Yoshi's Island: Super Mario Advance 3, Yoshi's Island DS, and Yoshi's New Island. It is similar in appearance to the individual platforms of a Paddle Wheel, but travelling on it is less dangerous, as the player only has to step on it once to make it start following the dotted line that it is attached to. When it reaches the end of the line and is blocked by a little red sphere, it will switch its direction of movement; if the line ends without a sphere, the Flatbed Ferry will fall down, but may be "caught" by another dotted line if it falls on one and starts following it.
There are three varieties of Flatbed Ferries, which only differ in their speed of movement. The green Flatbed Ferry is the slowest of the three types, the yellow Flatbed Ferry runs at a medium speed, and the red Flatbed Ferry is the fastest. When traveling on one of the faster types, quick reflexes will often be required to prevent being carried into an enemy or other hazard. Some Flatbed Ferries are on top of ghosts' heads.
Names in other languages