Omega Plants are giant Pirhana Plants. There not the new big plants in the New Super Mario Wii, these are much bigger. One even makes it as a mini boss in SMBX. To beat him, you need to keep shooting it in the head. If you try to sell his head, you'll get 30 coins.
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Type: Plant
Strangths: He is super big
Weakness: A whole LOT of fire
Hight: 40 feet
Weight: Unkown
Found: Swamps, Caves