A physical bitcoin BTC$66,661.06 from the legendary 2011-2013 Casascius mint had its hologram seal removed on Wednesday and the 25 BTC stored inside, worth $1.70 million at current prices, transferred to a new wallet.

Casascius coins were physical tokens created by software engineer Mike Caldwell in denominations of 0.5, 1, 5, 10, 25, 100 and even 1,000 BTC. Each coin had its receiving bitcoin address printed on the outside, with the matching private key concealed under a tamper-evident hologram on the back.

Holders could spend the bitcoin at any time by peeling the hologram and importing the private key into a wallet, a one-way move that destroyed the coin's collectible status.

Caldwell halted production in late 2013 after the U.S. Financial Crimes Enforcement Network advised him he was operating as a money transmitter without a license.

Intact-hologram Casascius coins continue to occupy an unusual category in collectibles markets. Each piece holds real bitcoin at face value and commands a numismatic premium for the physical artifact when sold intact in collector markets. Thousands of Casascius coins remain unredeemed across all denominations, trackers show.

Caldwell minted fewer than 20 of the 1,000-BTC denomination pieces, most of which are still intact and would each now hold the equivalent of roughly $66 million in bitcoin. While the project inspired a wave of physical-bitcoin successor mints including Lealana, Denarium and BTCC, Casascius remains the most collected by a wide margin.

Peeling a Casascius is a one-way trade with real economic stakes. Intact Series 1 large-denomination coins typically command a premium over their face bitcoin value, meaning the Wednesday redemption converted what could have been a higher-priced collectible back into pure bitcoin.

The redemption, recorded in Bitcoin block 952,159, arrives during a week of unusual activity at the dormant end of Bitcoin's UTXO set, with a 2011-era wallet moving 35 BTC after 15 years of dormancy.