http://www.helpinthecity.com/blog/cats-foxes-and-kitchen-sponges/
At this time of year foxes will be abandoning their earth and cubs will be sleeping above ground with their parents and going on foraging trips. Like puppies, fox cubs are very playful and will play tug-of-war with objects, chew on them and ‘hunt’ them. Playing is a natural behaviour that helps the cubs to learn vital skills that help them survive in the wild as adults. They are not born with the innate ability to hunt, but must learn this by experimenting with things in their environment. Unfortunately when foxes are living in close proximity to people they often have access to a wide array of ‘play items’ including shoes, gardening gloves, laundry, golf balls and sponges. I do not know why a sponge would be particularly attractive but it may just be something to do with the size and texture.
For all wildlife questions and information, please contact WildCall - Sussex Wildlife Trust’s wildlife information service

fox cubs / Hugh Clark