Double lobster

[Linda]

Very interesting. Any ideas why one would duplicate crayfish? I thought duplication was reserved for twins, or fish.

Yes, it is weird. I have no better explanation than idea that the artist was drunk, drawing from memory and decided they if there are two fish
then there should be two crayfish (crayfishes???)

Maybe it was aslo somehow inspired by the Cancer symbol. These are symbollic pincers of the crab but someone very poorly educated could think these are two crabs:
♋︎

I agree that perhaps they are both considered fish to the makers? Catching things in a stream is different than catching them from the ocean. You might catch both fish and crustaceans in the same way from a stream. Maybe it is why they have "fish" in the name in our vernacular?

Also evidently Pisces, Cancer and Scorpio make up the water signs. Perhaps the animal in Scorpio is bigger, or is not considered to be on the same level, as it is not a fish, per se, and so is not doubled, but is still shown with a line to a star.