I've just been watching my fish playing and noticed that my coconut cave has what looks like little balls inside it (from the bit I can see). I've got sand as substrate so it can't be gravel... They looked quite big too, about the size of a ball bearing. The tank has danios and bronze/albino cories as well as amano shrimp and an assassin snail. Would it be too stressful for the fishies if I took a peek or shined a torch through it? I'm really curious!!