Every sample throughout the year has the larvae of molluscs (called veligers) appearing in the zooplankton. February and March are months especially full of periwinkle eggs although even these can be found most months. Sampling from Dale Fort's jetty in the winter can guarantee eggs of the Small Periwinkle (Melaraphe neritoides) probably because of the high density of adults living on the concrete sides.

Veligers are particularly enjoyable to watch under the microscope as they are so dynamic. Even from an early stage there is a shell which they can withdraw into but when active the velum is extended so that two wheels of cilia create rapid movement.