Eels that help exfoliate your body by gently nibbling off the dead skin may sound like a happy convenience of nature.
But what would you do if this so-called helpful eel detached itself from the main buffet and headed straight for your genitals?
This is what happened to one man, who thought he would end up with softer skin, and instead ended up with the eel burrowing through his penis and into his kidney.
He then required three hours of surgery to repair the damage.
According to The Daily Mail, the story is of Zhang Nan, a 56-year-old man from Hubei province in China. The paper quotes him as saying: "I climbed into the bath and I could feel the eels nibbling my body. But then suddenly I felt a severe pain and realised a small eel had gone into the end of my penis."
Practicalfishkeepingco.uk (PFK) added: "Doctors spent three hours removing the 15cm/6" Asian swamp eel (Monopterus albus). The fish was dead when they retrieved it. PFK covered this story at the time, when surgeon Jin Wang, who performed the operation, explained that the eel’s slippery body greatly facilitated its unwelcome entry.
"He added: "The diameter of the urethra in a man's penis is just a little narrower, but because eels are quite slippery, its body worked as a lubricant and so it got into the penis smoothly."
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The eel treatment, and other more extreme forms of beauty treatment that lure people in with a gimmick-factor, have been highlighted by Wendy Nixon, a health and safety consultant, who last week told a conference hosted by the Chartered Institute for Environmental Health (CIEH), the body which represents health inspectors, that there were problems with the procedure.
She was also concerned at the number of treatments being performed by therapists not qualified enough to perform them - for instance fish spas, which feature Garra rufa fish that nibble off dead skin.
The Guardian reported her as saying: "I have been to big events for the leisure industry and they (the treatments) are working their way into gyms and these sorts of places, so keep an eye out for those. Anyone involved in these sorts of treatment should have at least a very minimum national occupational standard at a level-two pedicure unit."