I’ve been making sourdough on and off for years. This batch was parked beside the kombucha tea urn. Is that why it formed a kombucha tea-like SCOBY, or biofilm? This is the first time I’ve seen this happen. Beneath the layer all was well, the sourdough smelling nice and spicy. I took the layer off and fed the sponge. It’s bubbling away as good sourdough starter should.