Sourdough starter

...Or why you should not put it in a jar with a screw on lid.

That is not even the half of what I had to clean up in my kitchen afterward. No one was hurt, but the starter sure shot out well when Fixitman punctured the lid once we realized my mistake. Luckily a small amount stayed in the jar for me to salvage and grow into new starter. So it wasn't a total loss - just a pain to clean up.