Their medusoid bodies are bell-shaped, but some species lack the long, stinging tentacles frequently associated with jellyfish.    From Wordnik.com. Reference

Muller in his beautiful plates, and thus to trace the medusoid origin of the echinoderms, as the polypoid origin of the medusae has already been recognized.    From Wordnik.com.  [Louis Agassiz: His Life and Correspondence] Reference

Furnished with these facts, it is not difficult to recognize true beroidal forms in the embryos of sea-urchins and star-fishes, published by Muller in his beautiful plates, and thus to trace the medusoid origin of the echinoderms, as the polypoid origin of the medusae has already been recognized.    From Wordnik.com.  [Louis Agassiz His Life and Correspondence]

Even the degeneration of a medusoid from a free-swimming animal to a mere brood-sac (gonophore) is not sudden and saltatory, but occurs by imperceptible modifications throughout hundreds of years, as we can learn from the numerous stages of the process of degeneration persisting at the same time in different species.    From Wordnik.com.  [Evolution in Modern Thought] Reference