OK fisherdudes...what were these things?
 

Hi, all...

We have a large, slanting shelf of rock that sits under and near our dock. A couple of weeks ago, my wife noticed something interesting. There is a notch in the rock that forms an almost level shelf. On it were dozens of these little things, maybe 1/8 to 1/4 inch across. Up close, they looked like little flat polygons (not sure whether 5 or 6 sided), with 5 or 6 small white dots arranged around one in the center).

What were these things?

I posted here on the idea that they could have been some kind of fish eggs, but we didn't see any fish guarding them. If it was a nest, it probably wasn't in the best location, as slosh from boat wakes was disturbing them. They were gone after a few days.