The closed brain coral is probably Platygyra daedalea. To the right of it, in the
glare from the light, you might be able to see another fragment of
Hydnophora exesa, from Sanjay. The blurry brown strands in the
foreground are the branches of a Caribbean gorgonian that came on my
live rock.
Here's a Pachyseris with a case of RTN (notice the bare skeleton in
the middle). I removed the coral and treated it in 5 drops of 5%
Lugol's solution per liter of treatment water for 30
minutes. That seems to have stopped the spread of the death. The coral
is exposed to air at the top in this picture because the
circulation pump is turned off.
Two Tridacna maximas in my lower tank.
Blue Tridacna crocea in my top tank. Sorry about the blur.
Here's a Montipora digitata fragment that I won at a local raffle. When I
received it it was completely brown. Now it's taking on a green tint.