Throw it out, it has passed its use-by date, and don't replace it. I put a honeycomb weave teatowel on the floor of the shower and stand on that to stop me slipping. It goes into the washing machine with the towels so is always fresh and clean. Wet/soapy plastic gets pink mould on it.
When I turn on the shower, it runs cold until the hot water gets through the pipes but I have to stand in the shower to reach the controls to turn it on - so I cower against the wall holding the teatowel in front of me as though doing the dance of the one seven veils.