A local pet store had a chinchilla for a while when I was a kid in the 90s and the softness of its fur was just unbelievable, like it shouldn't be possible. I still think about it often and haven't felt anything like it since. The best comparison I can give is when you're tripping on shrooms and feel like you're experiencing completely new colours, tastes or sounds but it's more real. It was a defining sensory experience for me.