For the consideration of my fellow brewers…
The beer on the left was brewed January 1, 2015. The beer on the right was brewed January 3, 2015. The one on the left has what I'm calling a "yeast toupee", bits of krausen that have formed a sort of a lid over the beer. The beer on the right looks like what I expect: the krausen has sunk to the bottom.
These aren't the same recipe, but I'm suspecting that the main difference between these two beers is that I used three times as much Irish moss on the one to the left: one tablespoon for the last twenty minutes of the boil, vs. one teaspoon for the last ten minutes in the beer to the right.
I've seen this once before: that time I used a tablespoon of Irish Moss too. That beer tasted just fine, but it looked pretty disgusting in the fermentor.
So… does anyone know if this is what happens when you use too much Irish Moss? Or is this something else entirely?