When breeding, make sure your dinos are on passive or hitched. Alternatively put gestating female gacha on a spotp without vegetation..
Baby gacha autoharvest at birth and will hit their mother, as it's unclaimed it will aggro your dinos.
Gachas are essentially living lootboxes and resource farms. They will eat anything (including stone, wood, or fiber) and turb it into crystals which can drop a variety of resources including black Pearl's, organic polymer, or obsidian, among other things. They also have a rare chance to drop higher-tier crystals which turn into upgraded armor and tools