Hey it's the tooth of a sperm whale!
Very nice object!!
I'd love to find one, too - a blue whale once died on a shore nearby but I didn't manage to get her baleen - and my mom would have killed me if I had brought one home 
Is it empty inside??
Greetings,
Mauro.

Know that in my Region, during these times, people believed that knapped arrowheads were fallen lightnings: you may find buried small pots with burned soil inside, and these indicates the exact point were a lightning fell, in some day of the Iron Age 
Greetings,
Mauro.

Mauro Fiorentini wrote on Jan 21^st, 2012 at 6:22pm:


If they noticed that lightning on sand produces glass, they probably reasoned something similar happened on rock.

I once was going to buy a couple of rhino's teeth, but they were way too expensive... unfortunately!
By the way, Iron Age people in my Region seems to have been very interested in Neolithic artifacts - there're at least 2 knapped arrowheads that have been used as necklaces, toghether with a cracked stone axe, and another flint arrowhead has been found buried inside one of these tiny pots, toghether with burned soil - this is a habit I've tried to recall in a novel I'm writing.
And what Bruno said about sand, lightnings and glass seems perfectly reasonable to me!

Anyway, just out of curiosity:



here's a whale rib exposed outside a Medieval church in Modena, Central Italy.
Exposing unusual and weird things like these, ammonites, strange stones, etc... was a common habit during the Middle Ages, and was useful to show the faithful the magnificence of the nature, therefore showing them the infinite power of God. Plus this habit indirectly meant the beginning of collecting, which later evolved into museums 
Greetings,
Mauro.

Mauro, how on Earth can you be so sure that it is the tooth of a sperm whale and not some other type of whale!?

Hey, here's our friend 



Greetings,
Mauro.

About 5 years ago the puppy of a blue whale beached on a shore nearby.
She died months before and she was all yellow and rotten when she beached, nonetheless I went there and took a lot of pictures. Unfortunately, the carcass was so devastated that I could not take anything from it, but I saw a marine biologist who, armed with a huge knife and a thick glove, cut a square on the whale's body and put his whole arm inside her.
It was disgusting but the guy seemed to be in wonderland; later that week they managed to bring the corpse away from the shore.
They fixed it offshore and, after a few months, went there to pick up the bones.
We now have one of her teeth, and some other bones, at our scuba diving club 
Here's the puppy:



I love those creatures, my biggest dream is to meet them underwater and swim toghether!
Greetings,
Mauro.