The hymenium is highly convoluted and the spores remain trapped inside until the tuber is eaten by a rooting animal usually a rodent. The spores pass through the digestive tract unharmed and are dispersed in the droppings. To attract animals, truffles give off strong aromatic odours and even pheromnes that are sexually attractive to some animals. In sac fungi with apothecia, the ascospores are discharged violently. When ripe, an ascus explodes and shoots its spores into the air above the fruitbody.
Ascospores are so tiny as to be invisible.
This phenomenon is called puffing . If you approach a cup fungus carefully and breathe on it gently it may reward you by puffing. The tiny spores are carried great distances by wind to new sites for growth. The cleistothecium is a tiny sphere, usually less than a millimetre in diameter and is difficult to spot without a hand lens. Thousands of sacs with their spores are produced inside the cleistothecium and these are eventually released by breakdown of the outside wall of the fruitbody.