I played the remastered Spyro trilogy recently (great games) and it took me about half of the first game to work out how the gem chests work. You hit them and the gem shoots out the top, which you then have to grab before it returns in order to unlock the chest. For a while I thought you just had to ground pound the chest at the right angle to get it to open and I couldn’t work out why it didn’t always work.
After realising the correct way I felt pretty dumb lol.