I think I've got an alien.

Anyone familiar with this critter? I found it today in between two bags of compost - A bit less than 2 inch when curled up, but stretched out to about 4 when I first found it. It's quite fast moving. No obvious mouth. I'm suspecting New Zealand flatworm, which is a non native to the UK creature that eats earthworms. That's all I know about it.

Can anyone confirm my diagnosis? This is the first I've seen here, but I guess there could be lots more hidden away. I've put this one in a jar until I decide what to do with it.

Definitely. It's the dreaded eater of earthworms. I don't know if this hideousness is capable of eradicating them, but it sure seems to make a dent in populations. They're on the march in France.