f99a56df_Intertabrae_Chart__7
[0] Mollusca [1] Open System with a dorsal heart and sinuses [2] Gills [3] see Annelida [4] Sexual [5] Nephridia [6] Brain and ventral nerve cord [8] Anterior and Posterior adductor muscles [7] 
Some contain shells
S k e l e t a l
S p i c u l e s
N o n e
S o m e c o n t a i n s h e l l s
E x o s k e l e t o n m a d e o f c h i t i n
Intertabrae Chart
7