I'm not sure if you have any seashells, but I remember doing a project on Sea Shells a while back.

I had tons of shells that i've picked up over the years, researched them in the library and found out their names, and put it all on a presentation board.



I also remember once, making bones from the human body out of clay. Another easy thing, just get a book on human bones and form them out of clay, put them on a board with their names and you're done.