Mussels are not sentient. Would you have a problem with someone eating them and still calling themselves vegan? Sure, technically they are animals, but I'm more concerned with ethics than specifics. They have minimal to no affect on the environment when harvesting. My morals and standards still completely aline with veganism. I just don't see any reason to abstain. Mussels offer a great source for b12. They are also very healthy. I've watched many videos on the reasons not to, they don't make any good points. Unnatural vegan made a great video on this.