Red_Ruin said: Considering that a gold badged yukkuri can cost around £2k, you'd actually want it to be fairly durable, and not explode when you accidentally kick it.
good to see someone who knows real money =P
but yeah I would presume that by breeding or something ( I'd imagine yukkuris to develop quickly due to their usually short lifespan ) that they gain a resistance to stuff like twigs on a forrest floor without ripping their skin and waterproof enough to take like half a minute or so of rain ... but nowhere by any means invincible to rain or impact if you get what I'm saying.