Grand Master Krakatoa
A variant of Zoanthids (Zoanthus sp.)

Representative Zoanthidsphoto — a dedicated image of this exact morph isn't available yet.
A high-grade Krakatoa morph, typically a bright yellow outer rim with a pink/red center, the 'Grand Master' grade denoting the most saturated top-tier coloration of the Krakatoa line.
📜 Backstory
Sold (often abbreviated GMK) by World Wide Corals, Top Shelf Aquatics, Queen City Corals and many others, frequently as premium single-polyp or WYSIWYG frags at the high end of the Krakatoa naming line. A pricey collector grade; original Krakatoa lineage is debated.
Keeper tips for this variant
Place mid-tank under moderate, stable light and low-to-moderate flow; commonly sold as single-polyp or small WYSIWYG frags, so be patient as it establishes.
Other Soft Corals variants
RastasFruit LoopsUtter ChaosBrown/wild button polypsEagle EyeFire & IceRastaPeople EaterSunny D / Sunny DelightGobstopper / Bam Bam OrangeMagician / WolverineNuclear Green / Radioactive Dragon EyeRainbow IncineratorSunny DWWC BowsersMagiciansArmageddonBlue HornetGorilla NippleDaisy CutterTubbs BlueEverlasting GobstopperKing MidasWhammin WatermelonPink ZipperBamBamPink DiamondsGoblins on FireDaisy Duke's PalySpeckled KrakNuclear GreenArmor of GodPandoraRainbow HornetFire and IceBlow PopWWC Bob MarleyJF BloodshotEye of Ra