A cnidarian in which polyps produce medusae asexually and medusae form the polyps sexually is

Obelia is a cnidarian which exists in both forms exhibit alternation of generation (Metagenesis), i.e., polyps produce medusae asexually and medusae form the polyps sexually. Hydra, Adamsia and Meandrina exist only in polyp form. Medusa stage is absent in them.