They're shaped like comets? So... they're simply black comets. ANY variety of goldfish can be black, not only moors (but it's only the black telescopes that can be correctly referred to as moors). The thing is that the black color usually is "sticking" better to a moor and they usually stay black their whole lives. Since they're born bronze, they turn more black over time. Sometimes they start turning golden/red after a few years though. But like mentioned, that's more common in other varieties.
If you want to breed only the black ones, choose one pair in particular that you think have the strongest black pigment, and that have stayed like this for the longest time and try having them lay eggs in a breeding mop in a large tank/separate pond. There's unfortunately no guarantee that these fish WILL turn out black for sure, but if you're lucky, most of them will d: And even if they're black when young, they may turn red or yellow as they age.
It sounds like a really lovely pond, please post some photos