Jelly That Doesn't Swim - Halyclystus sp.

Haliclystus, an attached scyphozoan or stalked jellyfish (diameter ~2.5cm). You will find these medusae affixed to eelgrass or seaweeds in subtidal regions. They attach to surfaces by a stalk on the aboral side (side opposite from the mouth). When detached, they cannot swim and therefore move very little in a lifetime.

As seen here, they posess 8 marginal lobes that end in clusters of tentacles. Stinging cells or cnidocytes (a characteristic common to all jellyfish) are concentrated in these clusters. The sting of the cells is used to deter predators and to catch prey, mostly the caprellid amphipods abundant in eelgrass beds.