Experts are baffled by the discovery of a seemingly ‘alien’ corpse found on a Russian riverbank.

The four-centimetre skeleton of an unknown being was found in the Leningrad region in the town of Sosnovy Bor by a local woman named Tamara, The Age reported.

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But experts have been unable to determine what animal the shrivelled skeletal remains are from, although some of the woman’s friends believe it to be a mutated chicken embryo.

“It seems that this body is neither fish nor fowl… this creature has a mysterious skull, no neck and wings,” Krasnoyarsk Institute of Biophysics biologist Yegor Zadareev said according to a translation of an interview on Russian TV.

“Extensive studies are needed to determine what kind of creature or organism it is.”

But locals fear it may just be the product of nuclear mutation.

The town of Sosnovy Bor is located close to the Leningrad Nuclear Power Plant, and the residents remain suspicious of the effect it has on the life around it.