Ricko, on land the 'fura is surprisingly mobile and will grudgingly move out of a billabong in search of another if the conditions aren't good or to their liking.
I found Loch on my bedroom floor one morning, he had managed to negotiate what I thought was a 'fura proof lid, across the lounge, down the hall and into my bedroom, where I found him in the morning, curled up alongside my slippers. The traverse included polished wooden floors, carpet and a long strand woollen flokarti rug. I was extremely impressed.
I don't know how long they can last out of water, I would imagine if they can find a damp or humid spot to shelter, it would be be quite a long time.
waruikazi, if you found a 'fura 'living' in mud, it would be because of special circumstances, for example, drought where the water courses are drying up and the 'fura is desperately seeking moisture, in any form, to survive.