"But in the realm of TikTok or Instagram it feels so unnatural it's gone viral."

She also alleged that her husband used to threaten her and "beat me up after drinking alcohol and treated the husband-wife relationship like a beast" by demanding unnatural sex.

Biologist Tim Shields, who founded a company that develops tortoise conservation technology, was once opposed to head-starting because he thought it was unnatural and the tortoises would be inferior at survival.

At an inquest in September, a coroner said Ms Knights was believed to have died from a blunt force injury and drowning, and that the death was "violent or unnatural".

A recent study in the journal Science calculates just how much, reporting that — thanks to the near-total disappearance of commercial whaling — accidental ship collisions are now the leading cause of unnatural large whale deaths worldwide.