When one collects dead things, living at the beach is a good place to find new specimens. Dead animals wash up all the time. You get plenty of jelly fish, worms, and bits of sponge that aren't good for anything but throwing at old people, but you also get crustaceans, which you can preserve. Last winter, when I was no longer in lab and was writing my dissertation from home, I got to spend time walking the beach when taking a break (meaning that's what I spent most of my time doing). Something about that time of year makes dead animals wash up in abundance, or perhaps it's just that there are fewer tourists around to pick them up and throw them at old people.
But my largest dead thing is currently a horseshoe crab I found washed up near the dunes a couple of summers ago.
This is what he looked like after I first found him. He smelled bad. I used a little trick: I soaked him in water and put him on an ant mound for a week and let them have their way with him. Then I soaked him some more and put him in a bag with baking soda. That mostly removed the smell, so you don't detect anything unless you stick your nose right into his underside. Then I sprayed him with several coats of polycryllic finish, and, violin, I've got a preserved horseshoe crab.
I've since found other, smaller horseshoe crabs. Last winter I found two and was able to preserve them nicely. I gave them as gift to my niece and nephew. I'm sure the boy at least has destroyed his by now. I found a third really nice one that was perfectly intact with the meat still inside apparently. I kept it outside because of the smell until I could get around to performing surgery on it and removing the meat, but a damned raccoon did it first and tore the thing up.
I found this specimen below in what looked like a grave yard of dead conspecifics. I don't know what it was, probably seagulls, but there were legs and carapaces and other bits all over the place. I was able to find just one set of intact legs and one intact carapace, and they fit together just right. All the meat was out of it so all I had to do was glue it and spray it.