These were found on very old fluorescent light fittings before the canister types were used, they had SBC base and filled with Argon or Neon gas. They would of been seen poking out of the fitting normally at the ends
Yes its a bimetallic contact that makes contact to the other electrode. These were used on the first fluorescent in England I just remember seeing them on old fittings when I was a kid then came the large canister starter then the ones we see today