BLUEMOMENT

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The rash of strangely mutilated dead seals found recently round the Scottish coast is now thought to have been caused by them being sucked into ducted propellors.

BBC article.

Nick wrote:.
The rash of strangely mutilated dead seals found recently round the Scottish coast is now thought to have been caused by them being sucked into ducted propellors.

BBC article.

Mystery solved. In a news report a while back they said 'spiral' and I figured it would be a propellor of some kind.