Any exotic associated with a bounty is earned. Thorn must be earned, Bad Juju must be earned etc... Other exotics are FOUND. However strange coins are also earned and can be used to buy exotics. Those people who are complaining on this board about the injustice of Xur selling the IB, I hope that someone in your real life loves you enough for you to not need to get your self esteem from your video game possessions. Be excellent to each other.