Yeah, it sure was :) That's a nice species to come across as well, but luckily the swan mussel is not that threatened. We have it in Norway as well, but it's only been registered in three different lakes, so I don't expect to stumble across that one any time soon.
I see that you have the freshwater pearl mussel in the Czech Repulic too, but it's considered Critically Endangered there, so I bet it's rare to find.
Man, you never fail to educate me :) It is embarrassing for someone who consider himself a nature lover like me but I didnt even know we have the pearl mussel in my country! I just checked some Czech articles on this topic and you are 100% correct. It only lives in two little rivers in the south-western part of the country. Thank you for broadening my horizons again :)
Hehe, don't worry about it. It's impossible to know every single species you have in your own county! It's just too many of them :P