The "tusk" is as not real ivory as the day is long, I've seen hundreds of these at fleas and antique shows, they are meant to deceive. I agree that the rabbit also looks bad, and the elephant looks like real elephant ivory. Netsuke have been popular collector's items for many years and many have been made recently to sate the hungry market. Only the really old ones carry much monetary value. You would have to take the ivory one to a specialist to get a probable age and value. The best rule about ivory items is don't buy any unless you really know your ivory. It is also illegal to sell most ivory across state lines these days so it isn't a great investment anymore. Many states also now have laws against the sale of ivory items, especially elephant ivory so one has to be careful when trying to sell such items.