Shell dash
A Shell Dash is a move which Mario and Luigi can perform in New Super Mario Bros. They can only do it if they are Shell Mario or Shell Luigi. It involves dashing with a Blue Shell on them. They then duck into their shell and spin around like a Koopa Troopa when it has been kicked. In this form they can also break bricks and defeat enemies, but unfortunately Mario and Luigi only get 200 points for each enemy in a chain, but if they had kicked an actual Koopa, they would get increasing points until they got extra lives. The shell dash is slightly slower than the full running speed with other powerups, and it is hard to double jump with the Blue Shell and impossible to triple jump as Mario and Luigi would tuck into the shell and start dashing before they can do another regular style jump. The shell dash can be interrupted by another player in multi-player mode by stomping it, which will cause Shell Mario/Luigi to flip over onto their back, temporarily immobilized.