Bouncing blade

The Jar Cocoon (described as a spike creature or bouncing blade ) is an object that appears inside the second jar of World 5-2 in Super Mario Advance. It is a light-blue pointy object that lies on the ground, expanding and contracting repeatedly. If a playable character touches it, they lose a heart point. The Jar Cocoon cannot be taken out, as it is immune to the nearby vegetable and POW Block that can be plucked out of the floor and thrown at it.