Colonies are either free-living or attached; the former have a cone-shaped undersurface. Small colonies are oval shaped and consist of a central axial valley with short side valleys. Larger colonies are hemispherical and meandroid. There is a conspicuous ambulacral groove along the tops of valley walls. Septa are thick and even.
Colour: Usually uniform pale orange-brown but may be a variety of browns, greys and greens with contrasting colours of valleys and walls.
Habitat: Subtidal seagrass beds where colonies are small and free-living, also shallow reef environments where colonies are attached and become hemispherical.
Abundance: Usually uncommon.
Colonies commonly occur in seagrass, rubble or even sand.
The attached form may be a distinct species, M. mayori, and the final photo of an example with extended polyps may be this species (EW).