Yes, those are deffo daphnia cysts, not sure which species though sorry! I used to seperate them out from fairy shrimp and triops eggs you can buy mixed toether in dried pond detritus and hatch them in pure water with no minerals (like rain or RO).
I'm not sure what would trigger these ones to hatch exactly, for other branchiopods it usually involves a domant period for most of the cysts (a certain percentage may hatch sooner), and the cysts may be effectively indivdually "programmed" to come out of diapause under different conditions, usually something that signals fresh rain or flooding (water with very low mineral content). Warm temperatures and harder water tend to result in less live birth/quick hatching and more cysts being producded that are in diapause - as this is an idication that thier water sourcce is evaporating and might disappear soon.
You could skim them from the surface by putting a bit of kitchen roll or similar down and seeng if they stick to it, then dry them out and save them somewhere in case you ever need to start a daphnia colony from scratch.