Discovering a new species is always exciting, but so is discovering one that was thought to be extinct due to the passage of time.

A small clam that was previously only known from fossils has been discovered living at Naples Point, just up the coast from UC Santa Barbara. The discovery has been published in the journal Zookeys.

Rare 'fossil' clam discovered alive

(Photo : EJ Strat/Unsplash)

Finding alive a species first known from the fossil record is unusual, especially in a region as well-studied as Southern California, according to co-author Jeff Goddard, a research associate at UC Santa Barbara's Marine Science Institute, as per ScienceDaily.

Ours does not go back as far as the famous Coelacanth or the deep-water mollusk Neopilina galatheae, which represent an entire class of animals thought to have vanished 400 million years ago, but it does go back to the time when the La Brea Tar Pits captured all those wondrous animals.

On an afternoon low tide in November 2018, Goddard was turning over rocks at Naples Point looking for nudibranch sea slugs when he noticed a pair of small, translucent bivalves. He described their shells as "only 10 millimeters long."

"But when they extended and started waving about a bright white-striped foot longer than their shell, I realized I had never seen this species before," Goddard, who has spent decades in California's intertidal habitats, including many years at Naples Point, was surprised.

He immediately stopped what he was doing to photograph the fascinating animals up close.

Goddard decided not to collect the animals, which appeared to be rare, despite having high-quality images.

He sent the images to Paul Valentich-Scott, curator emeritus of malacology at the Santa Barbara Museum of Natural History, after determining their taxonomic family, Valentich-Scott recalled.

Along the American coast, the researcher is very familiar with this family of bivalves (Galeommatidae).

He mentioned a few possibilities to Goddard but said he'd need to see the animal in person to make an accurate assessment. As a result, Goddard returned to Naples Point to claim his claim.

But after two hours of combing only a few square meters, he still hadn't found his prize. The species would continue to elude him for a long time.

Nine trips later, in March 2019, and on the verge of giving up, Goddard turned over another rock and discovered the needle in the haystack: a single specimen, alongside a couple of small white nudibranchs and a large chiton. Valentich-Scott would finally receive his specimen, and the two could begin working on identification.

When Valentich-Scott got his hands on the shell, he was even more surprised. He knew it belonged to a genus with only one member in the Santa Barbara area, but this shell matched none of them. It raised the exciting prospect of discovering a new species.

The two scientists decided to investigate an intriguing reference to a fossil species. They found illustrations of the bivalve Bornia cooki in the 1937 paper that described the species. It appeared to be the same as the modern specimen. If confirmed, Goddard would have discovered a living fossil rather than a new species.

It is worth noting that the scientist who described the species, George Willett, estimated he had excavated and examined approximately 1 million fossil specimens from the same location, Los Angeles' Baldwin Hills.

Having said that, he never found B. Cooki by himself Instead, he named it after Edna Cook, a Baldwin Hills collector who discovered the only two known specimens.

monoplacophoran

Any of a group of primitive marine mollusks with a single, cap-shaped shell and bilateral symmetry known as a monoplacophoran (class Tryblidia), as per Britannica.

Tryblidia is preferred over Monoplacophoran and Galeroconcha because both terms include several fossil groups with uncertain relationships.

Several live monoplacophorans were dredged from a depth of 3,570 meters (approximately 11,700 feet) off the coast of Costa Rica in 1952.

It was previously thought that they had gone extinct 400,000,000 years ago. Fewer than ten species of monoplacophorans exist, including Neopilina galatheae, N ewingi, and N valeronis.

They have been discovered to depths of approximately 5,800 meters off the coasts of Central and South America.

The combination of primitive characteristics that monoplacophorans possess makes them unique. They have paired multiple organs with the single, cap-shaped shell, indicating at least partial segmentation (metamerism).

The gill structure and metamerism type suggest a much closer affinity of the mollusks with the annelid worms than previously thought; these features may also associate the mollusks with the arthropods.