Hunting beetle

But what make, I wonder?

I was carried away crouched down watching mining bees and cuckoo insects when this tiny beast popped out of a hole. I first thought it was a bit of moorland that had blown in from somewhere - until it popped back down again, retracting its claws first. I'd quite like to have seen it catch something but neither of us were lucky this time.

Update: I think this is the larva of a green tiger beetle which are on our moor. Look the larva up! I thought the adults were amazing—these beasts are awesome!