**Description:** A tiny, translucent aquatic worm that builds delicate tube-homes out of silk and silt on the undersides of rocks.
**Size:** Microscopic (less than 1 cm).
**Behavior:** Sensitive indicators of water quality. Their presence indicates high dissolved oxygen and a lack of chemical siltation.
**Identification:** Best identified by the presence of their tiny, flexible tubes which appear like fine fuzz on submerged stones.
**Habitat:** Clean, highly oxygenated riffles of the Allegheny and Clarion Rivers.