Reddit mentions of HDE Plasma Ball Lamp Light [Touch Sensitive] Nebula Sphere Globe Novelty Toy - USB or Battery Powered

I dunno what your budget is like, but once I started writing I came up with more and more ideas, idk if any of these are what you had in mind but the more ideas the better!!

For the food table you could do either a skeleton or corpse made out of cloths with food as the various body parts, I've seen some cool variations on this theme. Like, cake brain, ribs in the rib section, sausages for the intestines, breadstick fingers and toes with "blood" marinara sauce, etc.

You could have syringe jello shots (either alcoholic or non alcoholic) and either some kind of green drink or green food, I saw a cool "toxic waste" mac n cheese that was just white mac n cheese dyed bright green.

For creepy specimens, you can make a head in a jar: http://www.instructables.com/id/head-in-a-jar-prank/

Or, you could get baby dolls from a thrift store or masks in a jar with green liquid too. You can also get get some beakers and fill them with brightly colored liquid and put dry ice in them. I've seen places like spirit or party city have fake body parts and organs in steak packaging like you get in the store, you could always leave some of those around =)

You can get glow in the dark paint to splatter on some sheets, or have a turned over lab beaker with radioactive goo "spilling" on a table. Hide glowsticks behind other decorations, or in some stuffed white rats and other animals to make them glow. Have science goggles scattered around. You could have some of those novelty electric globes like this: https://www.amazon.com/dp/B004HFL73I
Or one of these: https://www.amazon.com/dp/B000PNINNI

I'll add more if I think of anything else!!

It's just a novelty plasma orb. You can usually find them in gadget/toy stores.

This is probably the one OP has. He mentioned it could either be battery or USB powered, which that one is.