It's a nice one, and rather
big - not the biggest size that can be found though which can be up to 6" tall - massive things - doorstoppers rather than for holding down bits of paper!
An early-ish piece, possibly mid '70s, in Tortoiseshell.
It is, however, marked
Mdina, not signed. The word "signed" indicates an artist's signature.
good luck with your sale.