Obsidian (ODN) describes itself as a Proof of Stake cryptocurrency which is used as a way to anonymously sign in to the Obsidian Secure Messenger (released on Google Play Store in late 2018). More information can be found at https://obsidianplatform.com
In September 2018, Obsidian cryptocurrency holders who freely registered on a time-limited claim portal were provided with a free airdrop of a new PoS cryptocurrency called ODIN, run as a non-profit co-operative organization. See https://odinblockchain.org for more information.