A carnivorous “death ball” sponge is among 30 previously unknown deep-sea species found by scientists in one of the most remote parts of the planet.

Researchers sampled the depths of the Southern Ocean, including volcanic calderas, the South Sandwich trench and seafloor habitats around Montagu and Saunders islands.

As well as the sponge, the scientists found new armoured and iridescent scale worms, previously unknown species of sea star, new crustaceans including isopods and amphipods, and rare gastropods and bivalves.

Experts are also assessing additional possible new species, among them black corals, and a potential new sea pen genus.

“The Southern Ocean remains profoundly undersampled,” said Dr Michelle Taylor, head of science at the Nippon Foundation-Nekton Ocean Census, which carried out the expedition. “To date, we have only assessed under 30% of the samples collected from this expedition, so confirming 30 new species already shows how much biodiversity is still undocumented.”

The spherical sponge, Chondrocladia sp nov, is covered in tiny hooks that trap prey, which is different to how sponges usually feed. Generally, sea sponges are passive filter feeders.

During a series of expeditions, researchers collected nearly 2,000 specimens across 14 animal groups. They also took many hours of high-definition video of these scarcely explored habitats, including the first confirmed footage of a juvenile colossal squid.