Square cloud

A square cloud, also known as a Cloud Block, is a block found exclusively in World 4-5 of New Super Mario Bros. Wii. It is white and has a smiling face on its front, making it look similar to Lakitu's Cloud.

When hit, a square cloud turns into a Lakitu that throws coins. However, the level also features Spiny Egg-throwing Lakitus that players can easily mistake for the coin-throwing Lakitus, as the two types are not visually differentiated.

Like standard Lakitus, Lakitus spawned from square clouds can damage the player characters on contact. Players can eat these Lakitus with Yoshi, gain points by defeating them, and ride their clouds as usual. Unlike the standard ones, Lakitus spawned from square clouds stay onscreen only temporarily and do not respawn.

Trivia

 * The way the Lakitu throws coins is reminiscent to Super Mario World when a Yoshi Cloud appears and drops Bonus Coins after Yoshi has eaten two Pink Berries.