Tongue / Slipper Plate (Herpolitha/Polyphyllia)
A variant of Plate coral (Fungia sp.)

Representative Plate coralphoto — a dedicated image of this exact morph isn't available yet.
Elongated 'tongue' or 'slipper' plate corals (Herpolitha, Polyphyllia) with a central seam and multiple mouths; same fungiid free-living habit.
Keeper tips for this variant
Lay it flat on open sand with room to inflate; these can creep slowly, so don't crowd them against rock or other corals.
Other SPS Corals variants
Red / Orange FungiaRainbow / Bicolor PlateTongue / Slipper Coral (Herpolitha / Polyphyllia)Green Plate (Fungia)Orange Plate (Fungia)Red Plate (Fungia)Rainbow / Ultra Plate (Fungia)Long-Tentacle Plate (Heliofungia)Aussie Ultra Red FungiaRainbow FungiaGold Fungia (Aussie)WYSIWYG Ultra Tongue Coral (Herpolitha 'Ultra')Insane Rainbow DiaserisDiablo DiaserisDante's Inferno DiaserisRed Devil DiaserisColor Blind DiaserisGlow Bug DiaserisRainbow Plate / Rainbow FungiaUltra Orange FungiaTSA Funky FungiaTSA Popsicle PlateReefGen Project-X FungiaRed Devil Horns Cycloseris