Are they sheets of bacteria? I remember reading in one of the bio pellet threads that some form sheets of bacteria. Can't remember the 'proper' name.
Nope, it is plastic for sure. When I get home I'll see if I can get a picture. If not, I can open the top and see about scooping it out. I have been keeping a close eye on this... I have the reactor outside of the sump in front so I can see it 360 degrees. I just wanted to make sure there is even tumbling and to watch for clumping. All has been well just minor adjustments of flow over time.