I like these eco sponges from Reusaboo. I've kept an eye out lately for alternatives to plastic based synthetic sponges given their un-environmentally friendly properties. One criteria essential for me was that any replacements should have - as did my regular synthetic variants - a side that would cope with harder scrubbing tasks. This is the case with Reusaboo as one side is a texturized jute for scrubbing, with the other side suitable for less heavy duty cleaning.