conversation piece

noun2

1. •
   An unusual item, such as a painting, or a tabletop knick-knack which encourages comment from visitors, and so helps to break the ice.

   • I don't think much of the sculpture in their front yard, but I guess it makes a good conversation piece.
2. •
   A painting of a group of people engaged in conversation or some other activity, popular in the 18th century.

   • The painting is a conversation piece without conversation and rightly regarded as one of the masterpieces of the Paul Mellon Collection at Yale. — 2001