bivalves
Bivalve with a blueish-black shell and a narrow end. Often forms large beds in the rocky intertidal.
Photo from Misjel Decleer via WORMS
Other images:
Distinguishing features: Blueish-black shell with rounded umbo.
Easily confused species and differentiation: Modiolus modiolus (MOMO)
Extended Description: Found in several habitats, including the intertidal and subtidal. Often forms large beds. Attaches to hard substrate using byssal threads.