Cool!!!
I only have one now, and haven't seen any for a couple of years.
The goby shippers are getting better at weeding them out I guess.
How many did you get and what size?
You'll probably be having pits dug in the gravel before you know it.
Looking again at the pics, however, I think Martin needs to take a look at these. They may, in fact, be Vanmanenia. The two species look so similar. Martin has had both and should be able to confirm the ID.
Regardless, they are cool.