Fish hatch from live rock

[Tropicr]

I have a friend who is setting up a new tank. The only thing in the tank for about 2 weeks has been live rock, until....now he's got about 30, 1/8 th inch long fish. All you can see are eyes, dorsal fins and tail. Now way at this point (at least for me) to tell what they are. Has anybody ever heard of fish eggs surviving on live rock and hatching?? Anybody want to guess what they are??