Prehistoric Fossils of Bizarre Plant-like Animals Found to Contain Geometric Ball-like Structures

Researchers have discovered geometric, hollow, ball-like structures in 80-million-year-old fossils of bizarre marine animals.

Palaeobiologists Jennifer Hoyal Cuthill and Aaron Hunter identified the strange structures in two species of crinoid—a group of almost plant-like animals commonly known as sea lilies that are related to starfish and sea urchins—according to a study published in the journal Palaeontology.

The shape of the structures resembles that of complex carbon molecules known as "fullerenes," which were one of the first nanoparticles—usually defined as particles between 1 and 100 nanometers in diameter—discovered by scientists.

Fullerenes, or "buckyballs," are hollow spheres of carbon atoms, which are connected in a lattice of pentagons and hexagons resembling the pattern seen in the structure of some soccer balls.

The most common buckyball carbon molecules contain 60 carbon atoms, however, this figure ranges from 20 all the way up to 100. Scientists first hypothesized the existence of fullerenes in the late 1960s. Subsequently, researchers synthesized them accidentally in the 1980s before they were found in naturally occurring materials, such as soot, cosmic dust and viruses.

This group of molecules take their name from the most well-known member "Buckminsterfullerene," which contains 60 carbon atoms and is itself named after the renowned American architect Buckminster Fuller, who is credited with popularizing the geodesic dome structure.

Geodesic domes are hemispherical, hollow structures made from a lattice of triangles that are able to support very heavy loads for their size.

"Within fullerene molecules, each carbon atom is connected to three others, to make a three-dimensional, almost-spherical shape. If we look at the spaces between these atoms, which form the faces of the 3D shape, they are always pentagons or hexagons," Hoyal Cuthill, from the School of Life Sciences at the University of Essex, U.K., told Newsweek.

The authors of the latest study discovered macroscopic structures—those that are visible to the naked eye—resembling buckyballs in ancient crinoid fossils representing two species, Uintacrinus socialis and Marsupites testudinarius, in the collection of the Sedgwick Museum of Earth Sciences at the University of Cambridge, U.K.

"Crinoids are relatives of sea urchins and starfish within the group of echinoderms," said Hoyal Cuthill. "Crinoids live mainly on the seafloor, though a few can swim with their long arms, which are more usually used to capture food and pass it to their mouth."

"Crinoids have a long fossil record, which includes strange body types that no longer survive today. Some especially bizarre examples are the two crinoid groups we studied, genera Marsupites and Uintacrinus, which lived during the Cretaceous period about 80 million years ago," she said.

The most distinctive features of these two crinoid species are their long feeding arms and a ball-like body part known as a calyx constructed of several plates made from calcium carbonate. Scientists think this body part helped stabilize the animals in the soft chalk mud of the seafloor to which they were attached, or acted as a buoyancy chamber to help them float in the water.

"Crinoids have a skeleton, under their skin, made up of many small plates joined together at their edges," Hoyal Cuthill said. "Part of this skeleton is the calyx which houses the mouth and protects the internal organs. In the two groups we studied this calyx has lost the usual anchoring stalk and is greatly expanded into sphere-like shapes around 7 centimeters wide."

"The calyces of the two groups we studied also show differences in their structures. Uintacrinus has a slightly larger calyx made up of many small, especially lightweight plates, while Marsupites has a somewhat smaller calyx made up of 16 larger plates, plus an upper opening."

Geometrical analysis of the calyx body parts in the fossils revealed structural similarities to buckyballs.

"Despite their totally different contexts, the microscopic fullerene molecules and the strange calyx of the extinct crinoid Marsupites have exactly the same shape and structure," Hoyal Cuthill said.

"The discovery of similar mathematical structures in fullerenes and extinct crinoids suggests that these animals also need calyces that were large and rounded. As well as this, the calyces of the two groups we studied appear to have been optimized in slightly different ways. Uintacrinus has a weaker calyx structure which seems to have instead been as large and light as possible. Marsupites appears to have needed a calyx which was as strong and stable as possible, while remaining large and rounded," she said.

with the authors suggesting that the shape of this body part may have provided an evolutionary advantage.

"Survival was critical and the ball-like structures, able to withstand very heavy loads, formed around them to protect them from the harms of the ocean and aid buoyancy," Aaron Hunter, an author of the study with the University of Cambridge and the University of Western Australia, said in a statement.

Marsupites testudinarius
Artist's reconstruction of the crinoid Marsupites testudinarius. J Hoyal Cuthill

"These animals could then spread around the world and have been found in chalk rocks from Texas, U.S. to Kalbarri in Western Australia. They could form a snow shoe to sit on the bottom of the shallow oceans or float and relocate to safer places," he said.

The researchers say that the calyx of Uintacrinus socialis was made up of more plates than that of Marsupites testudinarius, and these plates were also arranged in a more complex pattern.

"The structures are also found in the carbon molecule Buckminsterfullerene but this is the first time we have found such a structure in fossils and it still remains a mystery why these successful structures did not evolve again," Hunter said.

"Later, architect Buckminster Fuller would rediscover and popularize these structures and apply them to creating iconic buildings such as the Eden Project in Cornwall, U.K. However most would recognize the structure in the humble soccer ball we know and love," he said.

Despite the potential evolutionary benefits of the fullerene-like structure in the body of the crinoids, both species of crinoid became extinct by the end of the Late Campanian period—around 72 million years ago—as new marine predators, such as crabs, evolved.

This article was updated to include comments from Jennifer Hoyal Cuthill.