Space Wars

The hail isn't actually hail but is instead spores, which grow into the mushrooms. The spores are coming from a space-born organic creature called the Void Mushrooms, which are large fungal creatures that move and reproduce by ejecting fungal spores. The spores land on nearby planets and if they have enough nutrients, they grow until they eventually cover up the entire planet and combine into a massive mature void mushrooms, which then take off into space and travel in all different directions, conserving their energy until reaching another star and reproducing on the orbiting planets. The only way to deal with them is the burn the ejected spores with super heat lasers before they reach the atmosphere until the void mushrooms die on their own.