This enemy opens and closes its shell. When its shell is open, Shell'n will spit bubbles that will have a different pattern according to whether the Shell'n that spat the bubbles is over water or underwater. Over water, the Shell'n will fire one bubble with have a parabolic trajectory, while underwater there will be three bubbles that will float to the surface of the water. Shell´n is mostly invulnerable when shielded, but not when open. As an oyster-like robot, Shell'n is immobile, only attacking through its bubbles.
Overwater bubbles will have a range of 4 tiles, while the third bubble fired underwater will have a range of 6 tiles. In the underwater bubbles, the first one will float faster than the second one, and this latter from the third one. The distance between the first bubble and the second one are shorter than the distance between the second one and the third one.
- The 8-bit sprites were designed by Zedicon.