One wouldn't want to swim into Megalodon, the prehistoric shark. Much bigger than great whites, a megalodon tooth can measure up to 18cm long (just over 5 inches)! Since this is an illustration for kids, I tried to make megalodon look a little cute. Inked by hand, scanned in photoshop, neatened in illustrator, colored in photoshop, ultimately used for a activity station sign, made in illustrator.
2-12-08 update: Alas, this megladon was deemed too scary for kids. I will have to make him friendlier.