A mysterious golden orb that may be an egg laid by an unknown sea creature has been discovered on the ocean floor off the Pacific coast of Alaska.
The smooth object with an intriguing hole at the centre was found at a depth of about two miles by a remote-controlled submarine explorer.
Scientists at the National Oceanic and Atmospheric Administration (Noaa) in the US, which made the discovery, suggest it could be a hatched egg or a marine sponge.
Researchers are conducting tests and a DNA analysis to work out what the shiny object – which feels like “skin tissue” according to Noaa – is.
A remotely operated arm was deployed to “tickle” the egg, which was found to have a delicate “skin-like” texture. It was then gently “suctioned” up a tube for testing in a lab. The dive is part of the Seascape Alaska 5 expedition, which will continue until 15 September and can be followed on a livestream.
The mission is exploring the Gulf of Alaska, down to depths of four miles, including deep-sea coral and sponge habitats, and geological features such as mud volcanoes.
Speaking over the livestream on 30 August, when the discovery was made, team members offered theories about the identity of the object, including an egg casing or a sponge. They suggested that the hole was created by a creature hatching, or by a predator breaking in.
“I just hope when we poke it, something doesn’t decide to come out,” one scientist said. “It’s like the beginning of a horror movie.”
On images taken from the ocean floor, the object had a golden appearance, but this was attributed to the reflection from the submarine’s headlights. A photo of the object taken in the lab suggests a brown-yellow colour.
Several species, including deep-sea fish such as sharks, lay their egg cases on the sea floor, which makes them less likely to be washed away by ocean currents. Sponges are simple aquatic animals with dense, porous, skeletons that attach themselves to rocks.
Prof Kerry Howell, a deep-sea ecologist at the University of Plymouth, said that it is not unusual to find new species during exploratory missions, but that it would normally be possible to place them in a broad taxonomic category.
“We’ll often see new things but will usually have a pretty good knowledge of what they are. What’s unusual about this thing is we’re not even sure what it is. Is it an egg, is it a sponge, what is it?” she said.
“We’re going with egg because of the texture. It felt fleshy and it doesn’t have any obvious anatomy. It has a hole in it that suggests something has come in or gone out. But it doesn’t look like any egg I’ve ever seen,” she added.
“If it is an egg, the really interesting question is whose egg is it. It’s quite big. That’s not a small fish egg. That’s a sizeable thing.”
DNA tests should be able to establish which family of marine life the orb belongs to, although it is unlikely to be possible to identify a precise species since only a fraction of marine life has been sequenced.
