Simplify the following text for a Grade 7 native English-speaking person.
Original: Entoprocta , whose name means `` anus inside '' , is a phylum of mostly sessile aquatic animals , ranging from 0.1 t long .
Simplified: Entoprocta , or Kamptozoa , is a phylum of tiny sessile aquatic animals ranging from 0.1 to 7 millimetres ( 0.004 to 0.28 in ) long .