Rear pain of my display tank....

[lukel]

these little white things.... i don't know what they are.... i just noticed them... i don't even know how long they have been there.... i have them in my sump too... they are very small.... the one picture has a 3/4" bulk head in the backround for a size reference....
http://i678.photobucket.com/albums/vv149/lukelubinskyj/IMG_1026.jpg
http://i678.photobucket.com/albums/vv149/lukelubinskyj/IMG_1025.jpg

[SanJuan]

Those are tiny calcareous worms. They mostly develop in dark areas, and are a good sign that your tank is doing well.