Mesophyllum expansum is a species of red alga belonging to the family Hapalidiaceae.

[1][2] Mesophyllum expansum can reach a diameter of about 30 centimetres (12 in).

Illuminated by artificial light they show a beautiful pink color, with hanging branches.

These calcareous encrusting organisms can be observed occasionally near the surface and can reach a depth of 70 metres (230 ft).

[3] This species is widespread in the Mediterranean Sea.