Still no internet, so this is drafted on my phone. Well done to those of you who worked out that Friday’s object was indeed a rattle-snake’s tail.
I will expand on this answer, once I can use a computer to type comfortably!
Right, internet is finally working again, so here’s a (slightly) fuller answer to what this is:
As was mentioned before, this is indeed a rattlesnake’s tail. Rattlesnakes have a bad reputation for being aggressive and dangerous, but it should be remembered that they have a rattle in their tail to warn off predators and large unwary animals that might trample them – so at least they give fair warning.
There are quite a few species of snakes that make use of a rattle on their tail and this one comes (apparently) from Crotalus durissus, a South American pitviper that is quite dangerous due to their powerful neurotoxic venom (unlike the cytotoxic venom of the North American diamondback rattlesnake).
The rattle is formed when the snake sheds its skin – a section of the old skin is maintained on the tail as a “button” – these “buttons” are hollow and when they hit against the other “buttons” from previous sheddings, a susserating rattle is produced. See below for detail of the internal structure: