What they do is they cement to each other, and they build these huge, extensive reef systems. They can be kilometers long, they can be meters deep, and arguably, they're the most dominant influence on how healthy any coastal marine ecosystem is going to be, because what they do is they're filtering the water constantly, they're holding sand and dirt in place.
Se adhieren unas con otras y construyen estos extensos sistemas de arrecifes con kilómetros de longitud y varios metros de profundidad. Probablemente, son la influencia más dominante en la salud de un ecosistema marino costero, ya que filtran el agua constantemente, reteniendo la arena y la suciedad.