Baffled Anat Primo was strolling along the beach in Ko Lanta, Thailand, when she spotted the bizarre remains with its sharp teeth bared.
She said: “I was just taking a walk around sunset time with my dog and I just saw it lying on the sand.
“I was amazed, I couldn’t believe what I saw and I kept staring at it for a good 10 minutes.
“At the time I had absolutely no idea what that was.
“To me it looked like an alien or something out of a horror movie. The pictures talk for themselves I think.”
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In Anat’s photos, the creature has jaws bristling with pointy teeth, with another possible tooth visible deeper inside the mouth.
Its leathery body has no discernible fins, arms or legs, and few identifying features.
There are, however, some holes to be seen – including one that might have been an eye socket in life.
Anat, who lives in Chiang Mai but is originally from Israel, said: “It actually looked in much better condition when I found it a day before, but that time I didn’t have my phone with me.
“When I came back the day after I took all the photos.
“It was about 70 to 80cm long.
“I touched it with a stick to turn it over – I wanted to see what the other side looked like. It was surprisingly heavy.”
Looking for answers, the 45-year-old shared her photos with a local Facebook page.
One person suggested it was a snake; another said a type of fish.
But others thought that the jaws-within-jaws offered a clue.
Moray eels have a second set of jaws within their throat – and when a fish is caught within the main jaws – this second set launches forwards, dragging the prey back to be swallowed.
One person commented: “It’s a giant moray eel, and it looks like it died getting its prey stuck in its throat or something.
“It looks like spines sticking out of its throat – you can see the ‘canine’ teeth of their second jaws in there as well.”
Giant moray eels are typically found in Indo-Pacific waters, and are known to be common in the seas off Thailand.