Perhaps because you solved your question very fast, and because the users in this forum are top notch 
but it is always good to be cautious, just in case.
If I were OP then i'd be very cautious. I'd definitely import it in a trusted and legitimate wallet like electrum to see which crypto it is rather than using online service to know which cryptocurreny it is. Since OP already found that it is a bitcoin wallet and also possible in stellar so using online services won't one of the choice that OP will make. I have found some of my private keys and import it on a wallet like electrum even though it will take some time but it's safe rather than using online services. Let's just wait for OP to lock the thread and hope that OP won't disclose how much coins he has, his private key and not using services online. but it is always good to be cautious, just in case.