Spongia virgultosa, S. officinalis and S. agaricina probably arise from a single ancestor and, at present, colonize three different habitats along the Portofino Promontory cliff and deep rocks (Ligurian Sea, Italy) from the first 2–3 m to 100 m depth. S. virgultosa
evolved an encrusting shape to face the high water movement of shallow coastal water, whereas the two shapes (elephant-ear or vase) of S. agaricina are related to the interaction with the local water movement and the consequent sediment transport. S. officinalis is more variable
in shape and more euryoecious than the others.
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