Earlier quoted context omitted.
Please define "feel". They experience structural damage - yes, same as every other living organism or plant if damaged. If I tear dandelion in half it will emit poisonous juice. Does it "feel" pain though? I think no. The "feel" part probably can happen only in the sufficiently large brain, and lobster most likely don't qualify.
"Feeling pain" has never been a particularly intellectual experience to me. Pain isn't some sort of abstract thought, it's a raw sensation that the harmed flesh itself seems to feel. When I step on a lego I feel it and flinch away from it before I even realize it. I guess that sort of reflex is what you're calling "experience structural damage" but I say it feels like pain .
It's complicated.