This little guy does a simple task and will only set you back $3. I wouldn't exactly call it "necessary," but it's still a good idea. To find out what it is,
This device is called a Ceramic Pot Minder and it's meant to help keep your pots from boiling over. Just simply place it into the bottom of your pot when cooking or warming pasta, soups, vegetables or milk. When the liquid starts boiling, he'll start clanging around reminding you to tend to your cooking.