It's called a "pearl"

Ben and I were getting ready this morning, and he was reading the shampoo bottle. Then he informed me that when an "s" is on a word, its called a "pearl." I had no idea what he was talking about, so I said, "Hm!" Then, it dawned on me. I said, "do you mean "plural?" He said "Yeah, p-pur-pl-ur-al." :)