That’s a 45 RPM record adapter (also called a “spider”).

It’s a small plastic insert used with vinyl records—the kind with a large center hole (7-inch singles). You snap this piece into the middle so the record can fit properly on a standard turntable spindle.
The curved “arms” help lock it into place and keep the record centered while it spins.
If you’ve never used vinyl, it can look random—but it’s actually a classic little piece from the record er