Place some wondering snails in a dino leash in front of a gacha and over fill gacha with stone gacha will collect all of the achatina paste the snails drop. As long as there is stone in its inventory it wont eat the paste.
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