Biodegradable 8″ Acorns. Dissolves quickly in water. Urns are designed to fully breakdown in soil in 3 to 6 months. In a water burial they saturate in seconds and start to break down after several minutes once they are on the bottom. They’ll float for a short time before sinking but this can be controlled by weighing them with stones. The urns are made of a nature fiber and are strong and lightweight. All materials are nontoxic and kid friendly and biodegradable.