1. I am about seven centimetres wide and part of me once moved swiftly through the sea.

2. I am filled in at the back but I am hollow inside.

3. I am a souvenir from Fiji.

4. I open and close on a duel string clasp controlled by a small round wooden hasp.

5. The end of the string is fastened to an ivory tipped round wooden handle that is pinched in the middle. Owners do not like losing things like me.

Find out the answer next week...