For time immemorial, humans have imagined the existence of giant sea monsters. But what if there actually was a beast of a creature lurking in the Pacific Ocean? Here’s the lowdown on mysterious recorded sounds that suggest the possibility–and the eerily on point 1928 short story that lends a prophetic illustration to what scientist cannot yet explain.

In the 1960s, the US Navy set up a system of underwater microphones around the globe to keep track of Russian submarines. But over the last 15 years, several of unprecedented sounds have been recorded in the Pacific Ocean by the U.S. National Oceanic and Atmospheric Administration. Some recordings are easily explained by volcanic activity or iceberg shifts, but there are two notable exceptions: nicknamed “The Bloop” and “The Julia,” they’re too loud to be coming from any animal known to man.

“The Bloop” was recorded in the summer of 1997 and lasted just over a minute. After thorough analysis, the NOAA ruled out human activity, volcanic activity and vibrations of ocean currents. In 1999, every sensor in the Pacific Ocean picked up another sound that eludes all known explanations. That 15-second recording has since been dubbed “The Julia” it sounds like a watery voice saying the name. Its origin was 1,500 miles west of Peru–about 1,000 miles north of “The Bloop”.

In the absence of a viable scientific explanation, we can turn to famed science fiction writer H.P. Lovecraft’s short story, “The Call of Cthulhu.” In 1928, Lovecraft imagined an underwater monster called “Cthulhu” who resided in the fictional of city R’lyeh, located in the southern part of the Pacific Ocean. A beast whose form was part octopus, dragon and human caricature, it looked like a “pulpy, tentacled head surmounted a grotesque and scaly body with rudimentary wings.”

The origin of “The Bloop” sound is only 1,000 miles away from Lovecraft’s fictional location–and “The Julia” wasn’t too far north. The plot thickens: according to the story, a cult of Cthulhu followers believed their “old God”, who existed in a state of prolonged slumber, would “rise and bring the earth again beneath his sway. Some day he would call, when the stars were ready, and the secret cult would always be waiting to liberate him.”

Obviously, we don’t know that these artistic interpretations are true—all we know is that the Pacific Ocean is the largest unexplored frontier in the world. And it will always be fun to speculate.