Swamp Escape by Shell!
From the Super Mario Wiki
Swamp Escape by Shell! is a course which appears in the Story Mode of Super Mario Maker 2. It is Undodog's second job, and it is set in the forest theme and the Super Mario Bros. 3 style. The course has a difficulty rating of 3/4 stars. Completing the course causes a large Dry Bones Shell to appear, which Undodog stays in.
The course starts with the "Horror" sound effect playing. There is a pipe that gives out a Dry Bones Shell, which Mario must jump into. Mario must then ride along the poison while collecting coins. Soon after, there is a 10-Coin, and a tower of Grinders which Mario must ride over. Bull's Eye Banzais start appearing, as well as some safe stopping points for Mario. Later on, there is another 10-Coin and some Skewers. Along the way is a 30-Coin. Soon after this is the goal, allowing Mario to complete the level as long as he is in a Dry Bones Shell.
Names in other languages