This in not one big creature, not a snake, not a worm but several hundred individual caterpillars. The Australian Processionary Caterpillar lives in the Southern half of the country and eats leaves like most caterpillars, but that’s about the only thing it has in common with other caterpillars.
It lives in vast groups of up to 300 and weaves a silken bag which hangs in it's food tree, the bag can be nearly the size of a football. At night they all go into the bag and stay there until morning. In winter they spend long periods in the bag only coming out to feed when possible. If they strip the tree of leaves they march on mass to another tree and make a new bag. Eventually they pupate and turn into very ordinary moths with nothing outstanding or exceptional about them.
Those tiny hairs are so fine they get into the pores of your skin and irritate you for several days, other creatures like ants, lizards, birds etc are totally unable to eat them because of the fine hairs. Aboriginal Australians collected them on bark and rolled them on hot ashes to burn the hairs off before eating them…possibly the only predator they have.
As kids we used sticks to gently push them around into a big circle and they would follow each other for at least as long as it took us to get bored and wander off. I did accidentally touch one once when it rolled off a stick and onto my hand, by the time I'd put it down my hand was stinging. An hour later my hand was red and swollen and itched like hell for a few days…I never made that mistake again..
I came by this procession by chance as they moved from one tree to another way out in the bush and this time I had a camera with me, otherwise this is a very rare sight indeed.
* Babies feeding on a single leaf and the unappealing adult Bag-shelter moth
I know you didn't come here to learn so you have my sincere apologies.