Pocky & Rocky Reshrined

During one playthrough, you need to gain 10 lives (not in total, but so that at some specific moment there are exactly 10). These lives are either bought for coins or are in hiding places (photo not mine, thanks to neotiteke).
To get 300 coins in the first location, you need to farm blue flying jellyfish at the very beginning of the location, move away a little and they appear again.