“aka creepy water spider, well, sort of”
Have you ever heard the term “living fossil”?
No, we are not talking about great grandpa.
We are talking about Xiphosura, the Horseshoe Crab.
The Horseshoe Crab is fascinating!
It has hardly changed at all in the past 200 million years and is just about the only Arachnid that lives in the sea.
They are not swimming spiders (that would be creepy), but are classified by scientists as part of the Arachnid group of animals, like other land spiders are.

Early Ordovician (Arenigian)
Upper Fezouata Formation
Zagora, Morocco
69mm arthropod (positive). Extremely rare. First we have had and best we have seen.
Arthropod