Giant clams have wide variety of beautiful colours. The vibrance colours also indicates clam health. When healthy, Giant clams can live up to 100 years. Giant Clam lays on the ocean floor and remains on the reef for its entire life.
By day, giant clams open their shells so that the algae inside them get a chance to photosynthesise. This may also explain the mantle colors of giant clams. The idea is that the vibrant colors of giant clams are due to photosynthetic Symbiodiniaceae algae.
A single giant clam can indeed filter around 1,000 liters of sea water everyday for the largest clam species and around 400 per day for the species we have here in Koh Tao, helping to maintain a healthy environment for other species.