Thousands of maw sharks were spotted at an underwater pajama party off the coast of Australia.

The shower consisted of Port Jackson sharks, a species that lives in the southern coastal waters of Australia. The sharks are known for their somewhat bizarre appearance, with two distinctive ridges running from their blunt nose to the back of their head. The sharks, which can grow up to 1.6 metres long, are nocturnal and spend their nights hunting squid, octopus and crustaceans. Unlike many other shark species, Port Jackson sharks are not considered a threatened or endangered species.

The sharks were resting on the bottom of the Beagle Marine Park, a marine reserve in Bass Strait, which separates Australia from Tasmania to the south. A team of researchers from the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS) discovered the sharks during a recent expedition. Jacquomo Monk, a senior research fellow at IMAS and leader of the expedition, said in a statement that the scientists were searching the seabed with a remote-controlled underwater robot when they came across the sharks, which were “densely packed like a carpet spread across the seabed,” about 65 meters below the surface.

The sharks were a welcome but not unexpected sight for the research team. The team had observed a similar gathering on another expedition six years ago. The researchers had returned to see how conditions in the park had changed during that time.

“We were hoping to see the sharks again during this survey,” Monk said. “Seeing them twice in a 3,000-square-kilometer park is like looking for a needle in a haystack.”

What hadn’t been noticed before was that all of the sharks were female. “This raises more questions than it answers, but we know that males and females of this species often live apart except to mate,” Monk said. “We don’t know exactly why the females are here. Perhaps they are feasting on the local delicacy – doughboy scallops – before making the long journey north to lay their eggs. Seeing them again tells us that the area is important to them.”

A school of sharks was the plot of Netflix’s surprise summer hit Under Parisbut unlike the mutated makos from the film, the sharks of Port Jackson pose no threat to humans. Even in the very rare cases where they do bite, bruises and a torn wetsuit are the worst that can happen.