Microscopic view of the marine stalked animal Obelia geniculata showing eggs in one part and tentacles on another part of the colony

Obelia geniculata
Marine (saltwater) hydrozoan

Showing tentacles for catching food

Obelia geniculata is a genus of Hydrozoans.

Hydrozoans are a taxonomic class of very small, predatory animals, some solitary and some colonial, most living in saltwater. A few genera within this class live in freshwater. Hydrozoans are related to jellyfish and corals and belong to the phylum Cnidaria.

Britannica says this: Obelia, genus of invertebrate marine animals of the class Hydrozoa (phylum Cnidaria). The genus, widely distributed in all the oceans, is represented by many species. The animal begins life as a polyp — a tentacled, stalk like form resembling a small sea anemone attached to the ocean bottom or some other solid surface. The polyp asexually produces medusae, or jellyfish. Obelia medusae release sperm or eggs into the surrounding water, and the resulting ciliated larva eventually metamorphoses to produce a branching colony of polyps. Britannica, The Editors of Encyclopaedia. “Obelia”. Encyclopedia Britannica, 26 Nov. 2008, https://www.britannica.com/animal/Obelia. Accessed 31 December 2021.