Symbiots are the creatures most often described as harmless - I have heard this said, exclusively, by people who have never encountered a disassociated one. A symbiot that has lost its host does not simply stop needing; it needs more, and in this context available means within range and not moving fast enough.

Somewhere above Stannington, at the head of the Rivelin Valley, stands the Head Stone - also known as Stump John, the Priestley Stone, or the Cock Crowing Stone - a solitary megalith that local lore maintains moves its position depending on the migration of curlbeak. I have found it in two different locations on two separate visits and have no satisfying explanation.