The current understanding of molluscan phylogeny is shown below.
Horizontal cladogram (source:[1]):
Solenogastres
Caudofoveata
Palaeoloricata
Neoloricata
Monoplacophora
Gastropoda
Cephalopoda
Rostroconchia
Scaphopoda
Bivalvia
Early organisms which have been compared to molluscs include Kimberella and Odontogriphus.