These were used to call up fish! Put the leads in the water and turn the crank causing fish to die, float up and be collected... Looks like this one was tossed overboard when the gamey showed up,
If users other than OPs don't have it (and/or obviously, if OPs have the what is it answered and don't bother to update), at least Admins should, and should mark this with a big green check.
In any event, interesting one. I thought it might be a teeny model of a larger working engine. So, thanks Mud Hut! Learned something. And googled further to further learn.
[eta: Sorry swa2818 for assuming things. I hadn't checked the posting date and thought that since I'd already read a lot of What Is It threads that this had been posted weeks ago. But was totally wrong, and I'm sorry.]