The mystery of the 13-foot “sea monster” has been solved, LiveScience reports.

Last week, a 13-foot “sea monster” washed up on the shores of Luis Siret Beach in the Andalusian village of Villaricos. Given its appearance and size, the strange-looking carcass had some people speculating that a new sea creature had been found. According to LiveScience, the “sea monster” had a body part that appeared to be a pair of “horns,” fueling speculation that the creature was a new species.

“A lady found one part, and we helped her retrieve the rest,” Civil Protection coordinator Maria Sanchez told the Ideal. “We have no idea what it was. It really stank, as it was in the advanced stages of decomposition.”

Early on, some experts mistakenly concluded that the stinky carcass might be the leftovers of an oarfish. However, Dean Grubbs, an ichthyologist at Florida State University, correctly identified the remains. He even had an explanation for the “horns.”

“That is definitely a shark skeleton,” Grubbs told NBCNews.com. “The elements toward the back were confusing me, but those are the lower caudal-fin supports. The “horns” are the scapulocoracoids, which support the pectoral fins.”

Although Grubbs didn’t specify what type of shark was discovered on the beach, several other experts made educated guesses. David Shiffman, a University of Miami shark researcher, told NBC News via Twitter that he thought the skeleton might have from a thresher shark. Experts at Almeria24h.com arrived at the same conclusion.

Oarfish look very similar to what was found in Spain. According to the Florida Museum of Natural History, oarfish are listed in the Guinness Book of World Records as the longest bony fish alive. Its name comes from its highly compressed and elongated body or from the old theory that oarfish swim through the water by “rowing” themselves with their pelvic fins.

Was it obvious when you first saw the pictures that this strange-looking “sea monster” was actually the skeleton of a shark? Have you ever come across the remains of a sea creature while vising the beach? Share your thoughts and experiences in the comments section.