Anything made of willow lasts all over ten minutes with two of mine... slightly longer with the other two, but it still vanishes within 2 hours. ^^ I really wish that willow balls and stuff could be bought in bulk... Either that, or it's time I made my own, there are enough willow trees around here to work with. Wooden toys/blocks are completely ignored here, usaally in favour of the hutch/run/kitchen cupboards when inside... I just chuck a bunch of toilet roll tubes in with them, sometimes stuffed with hay, sometimes not... They all seem to love flinging things, and two of mine play a game that involves searching for all their tubes to pile in their litter tray - usually very neatly.