58 pure silver Monero coins with orange/grey enamel devoted to Helium Hydra produced in the end of 2017. Some coins have been sold and few more graded at ANACS.

These coins contain no loaded value but can be linked to XMR wallets with base58 ids engraved on the rims with a help of custom entropy for deterministic wallet at https://moneroaddress.org/

There is an auction going on for these coins at this moment:

https://bitcointalk.org/index.php?topic=3072082.msg31655914#msg31655914