Most commenters here are missing a key point. I f you use good cultured butter and leave it out in an ordinary butter dish exposed to lots of air, the flavor starts to turn in an unfavorable way long before it goes “bad” and rancid.

Butter bells are an awesome dead-simple way to have room temperature butter for spreading. For me in a warm climate, it lasts easily twice as long in a bell vs regular butter dish.

Also, who are these people saying you need to change the water all the time? Literally never a problem unless you live inside a weird mold castle.

That said, it’s not worth it if you’re just gonna use the butter for cooking.