Another day, another weird animal sighting in the Carolinas.

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Joe Grondalski and Shannon Ruff were walking along the beach on Hilton Head Island Tuesday when they came across what looked like a small head in the sand.

Ruff told The Island Packet that when she bent down to get a closer look, the creepy looking creature retreated into its hole. Later it popped back up, repeatedly opening, and closing its mouth.

The couple say they saw another a dozen of the mysterious little creatures over the course of their walk.

"Stumped" as to what they could be, Grondalski posted a photo to a local Facebook group and contacted the S.C. Department of Natural Resources.

Shrimp Eel Hilton Head Island
Credit: Shannon Marie Ruff

While their neighbors couldn't identify the bizarre animals, DNR told Grondalski that he and Ruff had stumbled upon several shrimp eels. The members of the snake/worm eel family are noninvasive and are harmless to humans.

"We've been living here maybe five years, but we've been coming to Hilton Head since the early '80s, and we've never seen anything like this," Grondalski told The Island Packet.

Erin Weeks, the spokesperson for DNR's Marine Resources Division who responded to Grondalski, told Southern Living that the couple's shrimp eel sighting was especially rare.

Shrimp Eel Hilton Head Island
Credit: Shannon Marie Ruff

"Our biologists spend hundreds of days on the water each year, but this was a first for several who saw the photo, as shrimp eels are understudied and rarely caught in our fishing surveys," Weeks explained. "They're native to South Carolina, but we don't know much about their habitat preferences or behavior."

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Shrimp eels, which can grow up to three feet long, burrow in the sand where they feed on small crustaceans and other invertebrates.

Speaking with The Island Packet, Grondalski said neither him nor Ruff were frightened of them.

"We're both animal lovers," he said, "and the ocean holds all kinds of strange creatures. It was more like, 'Oh my God, what is that?'"