Rolling Toy Block
From the Super Mario Wiki
The Rolling Toy Block is a circular shaped block that Wario can ram in to move along to an area where he can stand on top of it. This block lets him access places to grab coins or Diamonds. The only stage that Rolling Toy Blocks can be found on is Toy Block Tower, in the Topaz Passage. It behaves similarly to Chomp Rocks from the Yoshi franchise.