M. Doosey/Tulane University

Even if you're a diehard animal lover who tunes in to every episode aired during "Shark Week," you'd be forgiven for not knowing about the pocket shark. The very first one was found 36 years ago off the coast of Peru and since then, the species had never been seen again -- until now.

According to a new study published in the journal Zootaxa, the second pocket shark ever to be seen has been discovered. It was found in a batch of fish collected as part of a National Oceanic and Atmospheric Administration (NOAA) study conducted in 2010, about 190 miles offshore Louisiana to study sperm whale feeding.

Unfortunately, the shark wasn't found swimming in the sea. The fish obtained during the NOAA mission had been frozen and slowly sorted through by scientists. In fact, it took lead study author, NOAA biologist Mark Grace, three years to sort through lots of other frozen fish to finally get to the pocket shark, as reported by NBC News.

One of the clearest signs that Grace had stumbled onto something different was the fact that the shark had a "remarkable pocket gland with its large slit-like external opening located just above the pectoral fin," according to the research paper (PDF). Scientists are unsure about the pocket's purpose, but, based on research from a similar species, they think it might be used to release pheromones. While the shark's scientific name is Mollisquama, it's common name comes about because of this unique pocket.

The specimen Grace found is clearly a young pocket shark, measuring only 5.5 inches long. The last specimen found was a female who clocked in at about 17 inches along, according to NBC.

Adding to the limited body of research about this remarkable animal, Grace and his team also note that the shark's belly had "ventral abdominal photophore agglomerations" which, in non-science-speak, means it had a grouping of light-emitting organs on its underside.

Upon running tests on the shy species, NOAA Ocean Service genetics expert Gavin Naylor determined that the pocket shark's closest relatives are the kitefin and cookie cutter sharks. Like those sharks, the researchers theorize that in addition to eating smaller animals whole, the pocket shark might also feed by chewing out plugs of meat from larger creatures.

"This record of such an unusual and extremely rare fish is exciting, but its also an important reminder that we still have much to learn about the species that inhabit our oceans," Grace said in a statement.