Which structure is present in mollusks for feeding?

The development of $Mollusca$ is:

Open type of blood vascular system,presence of auricle and ventricle,and presence of haemocyanin respiratory pigment are the characters of

In mollusks,the body is protected by a shell made of which substance?

Secondarily asymmetrical type of symmetry is present in

The connecting link between $Annelida$ and $Mollusca$ is: