Whirls and whorls are easily confused words.
The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway.
Autocorrect suggests words that start with the same letters. It’s suggesting what word you may want to save time, but quite often, its suggestions are pretty off base. They don’t help you out, but they do make you laugh.
Whirls is a plural noun. Literally, whirls are swirling patterns, like funneling water or another liquid being pulled down from the center in a circular motion.
Whorls is a plural noun. Whorls are the wavy and loopy line patterns that form a spiral shape. They are found in wood grains, and found on the skin of some people’s fingers and toes.
The following story uses both words correctly:
Little Whitney loved to visit the lakes and rivers near her hometown. She and her dad often went canoeing. She dipped her whorled fingertips into the water whirls created by her dad’s paddle. Occasional fish swam up and softly nibbled her fingers. She realized she really loved nature. One day she would be an explorer, or park ranger.