what are distinguishing characteristics of entoprocta?
['Bilaterally symmetrical.', 'Body has more than two cell layers, tissues and organs.', 'Body cavity a pseudocoelomic.', 'Body possesses a U-shaped gut with an anus.', 'Body normally permanently attached to a substrate.', 'Nervous system is a central ganglion with a circum-oesophagal ring.']