Researchers recently happened upon an unprecedented sighting — more than 1,000 female octopuses huddled close together in what they describe as an “octopus garden” two miles beneath the waves in the Pacific.

The team was exploring the Southeast Davidson Seamount off the coast of California with Explorer Vessel Nautilus when they came across the incredible gathering of Muusoctopus robustus octopuses. Huddled close to rocks, many of the females were seen in an “inside-out” body position, which indicated that they were brooding. Some could even be seen clutching clusters of eggs in their arms.

Image: Ocean Exploration Trust/NOAA

It’s possible that these snuggling cephalopods have been there for quite some time—some species of deep-sea octopus have been recorded brooding their young for more than four years. During this time, the mother goes without food to vigilantly protect the eggs from predators and ensure they are continuously bathed in oxygen-rich water. After the eggs hatch, the mother often dies.

The scientists noticed that the water appeared to “shimmer” in the areas where the octopuses were concentrated, suggesting the possibility that warm water seeping out of the seamount was the reason that the females congregated in that particular area to raise their young. Unfortunately, the survey vessel wasn’t equipped with a thermometer, so the team doesn’t know for sure.

Image: Ocean Exploration Trust/NOAA

Only one other such octopus gathering has been discovered, though there were only an estimated 100 octopuses present. That group was recorded on the Dorado Outcrop off of Costa Rica. Scientists aren’t completely sure if it was this same species as the most recent find, however. The species spotted off of California is Muusoctopus robustus, a small to medium sized deep-sea octopus found in the northeastern Pacific.

Image: Ocean Exploration Trust/NOAA
The Nautilus expedition season continues until the end of November. See more amazing deep-sea sightings at www.nautiluslive.org