I always wondered what was inside ... now I know!
I needed to cut up a moss ball for one of my crazy projects. I placed half in a small dish and started with my project. I was happily working away and needed a bigger piece. I grabbed the half ball and saw something in the water in the dish ... 16 honking big planaria!
I, like many people on this site, have a battle against these wee beasties. Obviously they were living happily inside the moss ball. A long time ago I waged a war against them and obviously lost, then gave up. I took out the moss balls so the shrimp had something to climb on. They were not treated, not thinking they could be a major source of planaira. Now if I can ever find a source of fenbendazoleI will take the war to a new level!