It tastes fine

 The last batch of beer we brewed was in the in ferment for a long time. We were using a yeast that could be either a lager or an ale, depending on ferment temperature and duration in the bucket. Well, it was a bit warmer than ideal for lager, and we kind of forgot about it, so when I finally opened the brew bucket to bottle it, was shocked to see this.

I'm still not a pro at brewing, but this did not look like the other batches I had done, and at first looked like mold, which would have meant an air leak and ruined batch.  A frantic internet search turned up comments that sometimes yeast will form on top of the wort if left longer, and look sort of like this. Most advice said to just taste it, and if it tasted ok, bottle. So a cautious sip confirmed it seemed ok, so we bottled. After the requisite two weeks of carbonation, we cracked a couple, and it is indeed fine. One more lesson learned.