Snailicorn

Snailicorns are large snail-like creatures that have the characteristics of a unicorn, such as a large horn. They appear only in New Super Mario Bros. and are never seen outside of ice stages. They can be very dangerous, as a mere jump is not enough to defeat them, and fireballs are ineffective. However, as jumping on them sends them back a few feet, this tactic can be used to send them off of a cliff nearby though they'll reappear if Mario leaves the area and comes back. Also, a full-speed Shell Mario, or a stray shell will knock them out.

They will always charge in a straight line, but change direction at edges, similar to Red Koopa Troopas.

Trivia

 * Snailicorn is a portmanteau of snail and unicorn.