Um, Lobsters do have nerves and do feel pain. They just don't react to temperature-based pain the way that you do (aversion response).
"They just don't react to temperature-based pain the way that you do"
I pitty you if you don't curl up their tail and hold it that way until they quit kicking when you stick their heads in the water.
I saw an idiot just drop one in a pot one time and the thing almost emptied the pot of boiling water with it's tail.
No, lobsters do not feel pain. Their central ganglion is rudimentary at best. I spent 2 years studying lobster neural anatomy at Woods Hole, and wrote an even half-dozen peer-reviewed papers on the subject.
And then I became a lobsterman!