If you have a compost heap, cut them up and chuck them in, they'll be gone in a few months. You can cut them up and ad them to some council compostable collections too. Or, throw them in your bin, it's hard to say how long they will take to degrade in landfill as there are too many variable, but they will degrade eventually.

Normal sponges are made of plastic and they're not recyclable. So every plastic sponge you've bought, still exists, probably at the bottom of a landfill. Our sponges are natural and will degrade easily over time.

Forever! Ok, not forever, but they do last a long time. When they start to look mucky and tired, pop them in the wash or the top drawer of your dishwasher for a glow up.