Cliona viridis, commonly called the green boring sponge, is a species of demosponge in the family Clionaidae. Its form varies according to the nature of the surface on which it grows. In limestone and other calcareous substrates it excavates channels and chambers while on other types of rock it encrusts the surface or forms massive structures. It is native to the eastern Atlantic, the Mediterranean Sea and the Indo-Pacific Ocean.

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