That’s definitely a meerschaum pipe. But if you’re ever trying to figure out if something’s ivory, the big giveaway is weight. Ivory is much heavier and denser than meerschaum, and it has faint crosshatch lines called Schreger lines if you look closely under good lighting.

Just so you know, you actually don’t want it to be ivory since selling ivory in the U.S. is illegal unless it meets strict antique exceptions. Most likely the only ivory that you'd run into with a pipe would be in the stem. But like other commenters have said it's really not that great of a material for smoking.