Not sure if this is a fungus, scoby, or bacterial biofilm, or what? But I had this whitish slime growing (floating on top) in some bins filled with persimmons and water. Wherever it grew to about ~1/8" thick, it got pretty tough and rubbery - like it was hard to rip apart at that point. And also turned more whitish, like silicone. Before that, it was just like a slimy film with a slightly yellower tint.