Words that change completely:
* Child -> Children
* Tooth -> Teeth
* Foot -> Feet
* Man -> Men
* Woman -> Women
* Person -> People
* Mouse -> Mice
* Goose -> Geese
* Ox -> Oxen
Words with slight changes:
* Fish -> Fish (same, but can be used as "fishes" to imply different species)
* Sheep -> Sheep (same)
* Series -> Series (same)
* Species -> Species (same)
Words that change the ending:
* Box -> Boxes
* Brush -> Brushes
* Church -> Churches
* Dish -> Dishes
* Fly -> Flies
* Toy -> Toys
* Story -> Stories
* Berry -> Berries
It's important to remember that some words have both regular and irregular plural forms. For example, "octopus" can be "octopuses" or "octopi".
These are just a few examples, and there are many other words that have unique plural forms. If you're unsure how to pluralize a word, always consult a dictionary or grammar guide.