An ancient being has been hidden in Antarctica for 15,000 years; it could be the oldest life form on Earth (video).

The history of our planet spans over 4.5 billion years, during which Earth has become home to an incredible number of living beings, some of which can survive in the harshest environments. In a recent study, scientists unexpectedly discovered in the McMurdo Sound in Antarctica what they believe to be the oldest living organism on Earth, according to IFLScience.

It is known that the McMurdo Sound region is home to a species of sponge known as the giant volcanic sponge (Anoxycalyx joubini). Determining the age of individual animals is a challenging task, but the authors of the study believe they have found one of the oldest creatures on the planet.

Sponge organisms are quite fascinating, albeit not the most mobile. These immobile invertebrates, like corals, play a crucial role in the ecosystems they inhabit, providing shelter to smaller animals. They also exhibit far more resilience than one might expect.

According to experts from the National Oceanic and Atmospheric Administration (NOAA), the skeletal structure of sponges is well adapted to their specific habitats, allowing them to thrive on hard and rocky surfaces, as well as soft sediments like sand and silt. Research has also shown that some sponges can attach themselves to floating debris. However, these creatures are extremely rarely observed in a free-floating state.

It is known that water is filtered through the porous outer layer of the sponge, resulting in some movement, as well as providing food and oxygen while dispersing waste. Scientists have already determined that tiny hair-like structures called flagella, located within the sponge, create currents to filter bacteria from the sponge's cells and retain food. Their robust skeletal structure helps sponges withstand the significant volume of water flowing through them each day.

Researchers believe that sponges could potentially be the first animals to have appeared on the planet — they may claim the title of the oldest inhabitants of Earth. Giant volcanic sponges can grow up to 1.5 meters in diameter and 1.95 meters in height, typically residing at depths ranging from 15 to 144 meters.

In the new study, scientists sought to determine the age of giant volcanic sponges based on their sizes. The authors observed the sponges for 22 years and discovered that they require a long time to grow.

According to the study's authors, the largest giant volcanic sponge observed in Antarctica measured about 2 meters in length. However, scientists had never previously observed how these creatures settle or grow. As a result, the team focused on determining the age of marine sponges.

The results indicated that the age of one sponge reached approximately 23,000 years, with higher estimates suggesting that giant volcanic sponges may actually live up to 23,000 years. However, further analysis indicates that these ages may be somewhat exaggerated.

In their work, scientists used growth models that take into account biological consequences as well as geological events. According to co-author of the study, marine biologist Dr. Susanna Gatti, working on such time scales requires consideration of not only biological consequences but also geological events. Sea level fluctuations associated with the last glacial maximum (LGM - 18,000-22,000 years ago) likely left the 2m-S. joubini "high and dry," as sea levels during the LGM were 105-130 meters lower than today. Therefore, it can be concluded that no marine invertebrate on the Ross Sea shelf can be older than approximately 15,000 years.

As a result, scientists believe that giant volcanic sponges are likely the oldest animals on Earth, having existed in Antarctica for at least 15,000 years.