Recrystallization. During the process of metamorphism, the particle size of the rock may change by a process called recrystallization. For instance, the small calcite crystals in limestone, a sedimentary rock, change into larger crystals during formation of the metamorphic rock marble.
The reason why humming birds need long beaks is to be able to get the nectar from the flowers, kind of like how we need straws to drink out of to go cups. Humming birds also have very long tongues that also help this process. Since humming birds beaks help them get the food they need, it makes them more successful in their environment.
