What was I mining in 2008?

Hi all, I mined Bitcoin at various stages in my life. For example I found old wallets from 2012 with small amounts of BTC and cashed them out already some years ago.

There is still a big mystery, though. I lived with a friend in a shared flat until December 2008 and he recently remembered, that we were mining something with CPU power. We started back then with a tool like SETI at home but soon moved into the crypto sphere, where you could mine something of monetary value, even if it was very low back then. I also remember the process crystal clear and was under the impression that it was Bitcoin. I now read, that the first block has been mined at the beginning of 2009, which rules out Bitcoin. Does anybody know what it may have been? Thanks!