A necklace I made of a Portuguese Man O war. It’s still available for sale here: http://www.etsy.com/listing/87430196/portuguese-man-o-war-jellyfish-necklace
A very similar necklace is also still available here: http://www.etsy.com/listing/87429484/portuguese-man-o-war-jellyfish-necklace
Portuguese Man O Wars are not technically jellyfish, but are actually made up of a bunch smaller creatures called zooids. My sister in law was stung by one once, and they hurt a lot, but are not deadly.