Duobrachium

Duobrachium is a monotypic genus of comb jellies belonging to the order Cydippida, family unknown. The only species is Duobrachium sparksae.

Discovery
It was discovered and identified based only on video footage of three specimens after being observed by the Deep Discoverer robotic vehicle, operated by the US National Oceanic and Atmospheric Administration. It was first discovered in a canyon at a depth of 3910 m to the north west of the Puerto Rican coast in April 2015.

Physical characteristics
The animal has a rectangular shape when viewed in the tentacular plane, but oval from the perpendicular plane. It has two long tentacle arms which protrude from the centre of the sides of the body, and extend downwards. These are about a third as long as the body. These arms encase retractable tentacles which are approximately 30–56 cm long. The animals use these to adhere to the seafloor.