Cloud
From SMWiki
Clouds are white, cloud-shaped blocks with a smiley face on them.
Description
In the original SMW, Clouds are mostly placed in the upper screen half of a level, where they are not observable unless the player jumps very high or finds a vine which he can climb on. They also tend to be placed in a straight row since they are easily passable from both sides and the bottom, The top of the clouds is solid, so that Mario can walk on them.
Clouds often lead to a hidden gift in a level, like a Dragon Coin, 1-Up Mushroom, or even the rare 3-Up Moon
The faces of the clouds always consist of black eyes and a smiling red colored mouth.
In Super Mario Bros. 1 and 3, Lakitu rode around in clouds that looked like this object. Super Mario World 1 was the very first occurrence of him riding around in a different-looking cloud, and he's used that cloud for every game since.
Hacking Information
In Lunar Magics Map 16 Page, the Cloud appears on page 1, number 106
Clouds are also available under Standard Objects, as object 17-B. (Object 17-A is a rope ledge.) If you use this method to insert the object, you'll only be able to resize it horizontally.

