A crystal swan
A swan was a type of aquatic fowl indigenous to Earth. It was characterized by a long slender neck.
In 2367, when Keiko Ishikawa and Miles O'Brien were about to be married, Worf went to USS Enterprise-D's replicating center to create a gift for the couple. He was about to choose a crystal swan when Data mentioned that it was his understanding that the item selected should reflect the personality of whoever was giving the gift, and that the swan did not remind him of the Klingon. (TNG: "Data's Day")