5 “Extinct” Sea Creatures Later Found Alive

Written by Kristen Holder
Updated: November 2, 2022
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The ocean is a vast place, and it presents an environment that’s hostile to human life. This has kept us from exploring a huge portion of it. This also hinders our ability to accurately follow certain oceanic life. What are five of these extinct sea creatures that were later found alive?

Animals that are declared extinct or are historically extinct but come back from the dead are known as the Lazarus Taxon. Lazarus is a figure from the Bible that Jesus raised from the dead. Since extinct creatures later found alive have risen from the dead in a sense, they earned this biblical nickname.

When an animal is rediscovered, it needs to be completely unchanged from the form that it was last observed to be declared the same animal. Any animal that is rediscovered but has a new adaptation is considered a new species.

We’ll take a look at five extinct sea creatures found alive exactly as they had been observed a long time ago.

5 Extinct Sea Creatures Found Alive

These are five extinct sea creatures found alive:

  1. Monoplacophoran
  2. Neptune’s Cup
  3. Coelacanth
  4. Goblin Shark
  5. Protulophila

1. Monoplacophoran

Monoplacophorans are ancient deep-sea mollusks.

Monoplacophorans are ancient mollusks that were found off the coast of Costa Rica. These deep-sea mollusks were supposedly gone for millions of years before they turned up alive. They were found over two miles below sea level.

They lived out their heydey during the Paleozoic Era. They’re a prominent member of the fossil record from 500 million years ago. It also appeared that they had gone extinct during the Devonian Period about 375 million years ago.

In 1952, it was discovered that they weren’t long gone. We now know there are at least 29 species of these mollusks still around today. It’s believed that monoplacophorans may be the basis for the evolution of modern mollusks.

Scientific records show that some individuals had been found as early as the late 1800s. However, they were misidentified as limpets at the time of these early discoveries. They’re more closely related to chitons than they are limpets, though.

Their deep-sea habitats vary, and they thrive in mud, gravel, silt, and sand. Some have been found near thermal vents. They eat microscopic things like foraminiferans, sponges, and diatoms.

2. Neptune’s Cup

Neptune’s Cups are huge sponges that were believed to have gone extinct a century ago.

This is a type of sponge that was believed to have been harvested into extinction in the early 20th century. However, living specimens were found in the waters off the coast of Thailand and Singapore. In 2011, the first modern specimens were discovered.

Neptune’s cup was believed to have gone extinct in 1912. Since its rediscovery, Singapore has relocated some individuals to a sanctuary in an attempt to better protect the species.

They are subject to predation, especially by map pufferfish and copper band butterfly fish.

Unfortunately, these fish are present at the marine sanctuary. This has slowed conservation efforts.

Living individuals have also been discovered off the coast of Cambodia since around 2017. They were discovered by people in search of seahorses on sandy bottoms. Neptune’s Cups are unique sponges because they anchor onto sand instead of using a reef.

3. Coelacanth

Coelacanth pair underwater

Coelacanths are huge deep-sea fish that were rediscovered by fishermen.


The coelacanth is an older example of an extinct sea creature that was found alive. It was rediscovered in the 1930s which is a century after scientists began studying their fossils. A fisherman accidentally caught one as a bycatch.

It was sensationalized as a living fossil by the media outlets at the time. Other living fossils include frilled sharks, horseshoe crabs, and crocodiles. A living fossil is an animal that has existed in the same state for millions upon millions of years.

Before the rediscovery of these fish, it was believed they had disappeared from the planet over 65 million years ago. They were members of the Cretaceous Period that were thought to have gone extinct with a myriad of other life on the planet at the time.

They’re one of the oldest examples of jawed fish available. They hang out in deep waters that reach over 300 feet deep. They have long lives and reach up to 100 years old though they average about 60 years.

They’re big fish that weigh up to 200 pounds and they reach lengths of 6.5 feet.

4. Goblin Shark

Goblin Shark

There may be a lot of

goblin sharks

in the deep ocean.

©Peter Halasz / CC BY-SA 3.0 – License

These rare sharks live in the depths of the ocean so it’s not a huge surprise that they were able to go missing for a long period.

It’s believed they’ve been around for around 125 million years and that a sizeable population may live in the depths. No one knows for sure, however.

Because they live at such extreme depths, they have terrible eyesight. These sharks live up to 60 years. They protrude their jaw forward more than any other extant shark when they strike at prey. Their strike speed is also amazingly fast.

These adaptations exist because the deep ocean environment doesn’t offer much food. Opportunities that do arise need to be dealt with swiftly.

Goblin sharks are part of an order of sharks referred to as mackerel sharks. They are the only mackerel sharks that spend their lives in the deep parts of the ocean. One specimen was found around 3,600 feet below the surface. As with some other mackerel sharks, goblin sharks take their prey down by ramming it.

They’re quick swimmers so they can reach top speeds before ramming into their meal. Fish make up a majority of their diet.

5. Protulophila

Protulophila are tiny worms that live on the armor of tube worms.

Protulophila are small marine worms that were believed to have gone extinct four million years ago but were later found alive. Their specialized environment includes the armor on tube worms that are made out of specific mineral makeups.

While some of their closest relatives are sea anemones and corals, these microscopic creatures are tiny in comparison. They’re less than .004 inches in length. Like the coelacanth, protulophila are considered living fossils.

These sea creatures go through two life stages. They start as an anchored polyp before they bud into a microscopic jellyfish. Protulophila have been studied off the coast of New Zealand where a variety of other microscopic jellyfish live.

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The photo featured at the top of this post is © AlessandroZocc/Shutterstock.com

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About the Author

Kristen Holder is a writer at A-Z Animals primarily covering topics related to history, travel, pets, and obscure scientific issues. Kristen has been writing professionally for 3 years, and she holds a Bachelor's Degree from the University of California, Riverside, which she obtained in 2009. After living in California, Washington, and Arizona, she is now a permanent resident of Iowa. Kristen loves to dote on her 3 cats, and she spends her free time coming up with adventures that allow her to explore her new home.

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