Dipsastraea maxima

Dipsastraea maxima

It is a coral of the familly Merulinidae.
Knob Coral Dipsastraea maxima I am pretty sure is Dipsastraea, the sp is more tentative butlooks it can be the one. 
Corallites large and round, oval or polygonal. Septa regular, thickened at the wall and with well-developed paliform lobes lobes forming a crown around the colunella. Brown or yellow brown with pale green oral discs. (description from Corals of Australia and The Indo-Pacific by J.E.N. Veron, page 463). Dipsastraea maxima,Fall,Geotagged,Indonesia,Knob Coral Dipsastraea maxima

Appearance

Colonies are massive and usually small. Corallites have well defined walls. Septa are regular, thickened at the wall and with conspicuous paliform lobes forming a crown around the columella. Polyps may be fleshy.
Colour: Brown or yellow-brown with dull green or white oral discs.

Naming

Synonym: Favia maxima. It has been reclassified not as Favia from Faviidae family but as Dipsastraea from the Merulinidae family.

Distribution

Indo-pacific from Thailand and Malaysia to New Caledoonia and Australia.

Behavior

The polyps are large and fleshy and active at night.

Habitat

Upper reef slopes.

Food

They live in symbiosis with zooxanthellae whose products mostly nourish them.

References:

Some text fragments are auto parsed from Wikipedia.

http://www.coralsoftheworld.org/species_factsheets/species_factsheet_images/favia-maxima/
Book: Corals Indo-Pacific Field Guide by Harry Erhardt and Daniel Knop, p 183.
http://www.marinespecies.org/aphia.php?p=taxdetails&id=758230
Taxonomy
KingdomAnimalia
DivisionCnidaria
ClassAnthozoa
OrderScleractinia
FamilyMerulinidae
GenusDipsastraea
SpeciesDipsastraea maxima
Photographed in
Indonesia