My wife and I are brewing another batch of our peach ale. Just got done racking our beer from the primary to the secondary.
For those of you who aren't familiar with home-brewing, the beer is transferred (racked) from one vessel to the next to keep the beer cleaner. The picture below shows the main reason why. The short version of what this stuff is in the bottom of the primary vessel is Yeast Poop. After the yeast converts the sugars into alcohol and CO2, there is a remaining byproduct that gets left at the bottom of the bucket. Sure makes beer look more appealing doesn't it.