Congratulations Fran. Not only did she answer the “What the heck is this?” correctly, she was the first commenter.
Here is the original item:
It is of course a gas discharge tube. You put these tubes in there (as shown above) with helium or neon or whatever in there and it excites the gas to give off light.
Honestly, we have like 10 of these things laying around. Some of them are newer and say “Danger 5000 volts”), but these older ones say nothing. Here is an example of one of the first ones I saw.
I didn’t figure out what it was for a while because most of the ones we have don’t have those metal clips that hold the tube – just two posts sticking up.
This seems like a super dangerous design. For comparison, here are two other models (that we actually use).
The one on the left is the older one (isn’t it obvious). You could stick your fingers in the two white tube holders and shock yourself, but you would have to try. The newer one is pretty much safe for toddlers. The only dangerous part of the newer one is that you could drop it on your foot. Of course you can’t even change the bulb.