I wish more people have read the Hyperion Cantos
so I could share this with them (I'm looking directly at you Mike). Very minor spoilers follow: in the series there is what is called the "cruciform," fist-sized coral like parasite that grow in huge numbers along the walls of planet Hyperion's labyrinths. Once worn, they slowly attach to a human and spread countless tiny tendrils throughout the body, and when you die they bring you back to life, slightly less intelligent, and, with enough resurrections, sexless.
Anyway, my dad brought me back a crucifix from Argentina that is large, and made of shell so it looks sort of like coral. Creepy. My dad is really an evil AI agent of the Techno Core (if you don't get it, read the books. They're excellent)