Eridat was a type of fine rug common on Betazed. Lwaxana Troi's great-great-grandmother commissioned an Eridat rug as a wedding present for her son, which became a family heirloom. It was eventually passed down to Lwaxana, and was destroyed during the Dominion invasion of Betazed. (ST short story: "The Ceremony of Innocence is Drowned")