So, a sea-glass bottle.
He examined It again, turning it in his hands, rubbing his fingers over the curves. It looked shapeless, but, as with the galleonfee cloth, his hands detected a shape his eyes didn’t see.
It’s a horse!
The mane was wavy in both senses, the forelegs were fused, and the hindlegs folded as if the animal was diving, seal-like, in the ocean.
Not a horse. It’s a kelpie!
He laughed, pleased with his discovery.
Kelpies were braeside fables, said to inhabit lochs and deep bays.
They didn’t exist, unless they were extreme examples of mutable fay. Someone had fashioned this one though, and it had ended up in the ocean.