How do bivalves remove unwanted particles as pseudofeces?

In bivalves, the process of removing unwanted particles as pseudofeces is a critical part of their feeding mechanism. While gills (or ctenidia) strain suspended material from the water, the labial palps act as a sorting station for this collected organic material.12

The inner pair of labial palps uses ciliary currents to transfer selected food particles to the mouth. Conversely, the outer palps sort the remaining, unwanted particles and consolidate them into a mucus-bound mass known as pseudofeces. These masses are then ejected from the animal through periodic contractions of the adductor muscles.1