Very difficult to get focused well and this is one of the best pics. These are ~1/8" long. Wife bought a lot of pods from reefs2go and I bought plants from aquacon about the same time. This is in the 50 gal refugium. I am pretty sure that these came with the pods. One of my fish guys said they are flat worms, but I am not finding anything quite like these online. They have been stuck to the glass in low flow areas, top to bottom, since I put the pods in.