Bonemeal is a dry powder made by crushing animal bones. Gardeners mix it into soil to feed plants. Crushed bone is rich in a plant food that helps roots and flowers, so bags of it sit in garden shops, not in the kitchen. It is a farm and garden word, a little old-fashioned on the label but still in use. The same powder is sometimes put into animal feed, but the learner's meaning here is the plant food. It looks nothing like a dinner; it is dust from bones.