From the Super Mario Wiki
Retrieved from "https://www.mariowiki.com/index.php?title=Anvil&oldid=2233436"
Anvils are angry-faced weapons similar to Thwomps appearing in the final pages in Yoshi's Story, where they are carried by the Black Shy Guys inside Bowser's Castle. If Yoshi walks near the anvil-carrying Shy Guys, they will release it and it will crush whatever is beneath it. They appear in the levels Lift Castle, Ghost Castle and Mecha Castle.