Look at the Dregs

Dregs are the leftover "things" from fermentation, like dead yeast, sediment from the finings and skin from the berries.

Most often the dregs rest on the bottom of the carboy. As you can see in the picture below some of the dregs collect on the sides of the carboy.

These dregs where placed on the sides of the carboy due to aggressive fermentation of the blackberries.

It's nice to know that racking wine leaves the dregs behind and produces clear wine, at least most of the time. I rack my wines several times before bottling to ensure clear wine every time.