I've continually thought that tests like the mirror test were inadequate at telling us whether or not an animal has some subjective self-awareness or internal thought outside of survival; or equally, that it means anything significant. It seems to me that each animal has a particular set of thoughts that govern their actions which are brought about by their genetics and environment.
Similarly, I've seen people close to me point out that dogs engage in empathetic group behavior while it seems some fish do not. But that seems like a silly line to draw on their value. After all, there are many traits that animals of different species posses that we do not. Yet, we do not put them on some pedestal of worth because of that. For example, the banded archer fish is capable of performing calculations to arch a stream of water to hunt flying insects above water. Meanwhile, my dog struggles to catch a treat falling towards his mouth.
Maybe, it could be argued, that certain very low thinking animals such bivalves are indeed not worthy of consideration. Not because they lack subjective features like empathy, self-awareness, etc, but because they lack thinking at all - like a group of individual organs communicating without a central thought collector to organize it - unlike most other animals. It is possible that new evidence will come out about specific neural capacity for bivalves, but for now, I am about as convinced as I am for most plants and fungi.