WATCH: Strange 'Alien-Like Creature' Seen Pulsing Through California Lake

A stupefied rower traveling across Lake Merritt in Oakland spotted a "slimy alien-like creature" with "spindly tentacles" pulsing through the water, and was able to capture video footage of the event. According to KTVU, the invertebrate is not an alien at all, but possibly a species of hydrozoan jellyfish scientifically referred to as Gonionemus vertens. Commonly called the "clinging jellyfish" this creature is characterized by an x-shaped design within its hood and medium-length, whiteish-blue tendrils.

Video footage shows the interesting invertebrate pulsing back and fourth through the water with very quick motions.

After watching the video, officials believe that the creature could be one of three species of freshwater jellyfish. Long Beach's Aquarium of the Pacific senior director of fish and invertebrates Nate Jaros told KTVU that the jellyfish was not easy to identify upon first glance.

"Without a thorough examination of the anatomy, the identification of most hydrozoan sea jellies—like the clinging jelly—is challenging."

While Jaros believes the jellyfish to be a Gonionemus vertens, the Marine Science Institute thinks that it is a Craspedacusta sowerbii because of its ability to exist in freshwater and its bell-shaped hood. In opposition to both sources, the California Department of Fish and Wildlife compared the invertebrate to a Maeotias marginata; a hydrozoan typically found within the same region of discovery.