Anyone recognise this mystery item?

[AMB]

Found this in the dog park, covered in mud. Does anyone know what it is?
At first I thought it was a dog whistle, but doesn't seem to do anything, cant blow through it very effectively.
In the first picture the small pyramid shaped part on the left is a pretty strong magnet and is fixed in place. That part of the rubber case is not connected to other end.
In the second picture, I have pulled the inside part out. You can see a slit in the side of rubber case, where I thought air must go in or out when you blow.
Third picture is a side view, showing the two orifices. Looks like a whistle, but I did a thorough search, and there is nothing that looks even remotely like it.
4th picture shows a profile of the metal insert, orientated the way it goes into the rubber case.