i have the same thing that just came out of no where today, my tank has LR and LS thats been running about 2 weeks. ive been keeping a close eye on my tank for hitchhikers and havent seen any and i turned on my light and saw like 25+ of these things crawling on my glass. they are white and about 1mm in length and are thin. it looks as if these things are crawling like slugs/snails. any one knows what it is?