A bitcoin transaction with a 291 BTC fee worth $136,700 was processed as part of block 409,008 on the bitcoin network today, sparking speculation as to the nature of what many are considering a colossal error by an unknown user.

The fee, one of many sent daily to pay bitcoin’s mining network for processing, managed to draw attention on social media due to its notable size. The average cost to clear a transaction on the bitcoin network was 31 satoshis, or roughly $0.01 at press time, a factor providing evidence of a potentially erroneous transaction.

Now, bitcoin mining pool BitClub, which claims to operate two mining locations in Iceland, has sent an email to users in which it asserted that it mined the block. BitClub said it earned a total of 316 BTC (or about $147,000) in fees, the figure equalling the fee plus the 25 BTC network reward.

However, in the email, the mining pool said that it is willing to return the fee, should the user come forward and identify themselves.

BitClub wrote:

“We are currently waiting for someone to reach out to us and claim their mistake so that we can verify them and send their bitcoin back, but so far as of this posting nobody has been able to verify it.”

Brock Pierce, chairman of the Bitcoin Foundation, told CoinDesk that BitClub has reached out to trade organization, offering to donate some of the funds should the user not reveal themselves after one week’s time.

“We would like to provide a portion to Bitcoin Core development, and will be open for other allocation options that benefit the community as a whole,” BitClub’s email read.

The mining service said it has been researching the transaction and that it believes it was possibly sent by a bitcoin mixing service, a type of online offering aimed at privacy and anonymity but that is nonetheless associated with illicit use.

Pierce said that he believes it is unlikely any users would come forward due to the risks of being associated with any large, potentially unregulated transactions.

BitClub sells three different mining pool products, though it has been the subject of speculation due to the anonymity of its owners.

At press time, BitClub did not respond to requests for further comment.

Missed dart image via Shutterstock