These are Hippocampus bargibanti and they are about 1.5cm (3/5 of an inch). There are a number of other pygmies and as the love of underwater macro photography spreads I think people will find more and more as they know what to look for. This species lives on red or more rarely yellow (as in the first photo) sea fans and their skin reacts with the fan and grows a similar coating of bumps and tubercules making them almost invisible. Having found them I took a couple of shots but unfortunately my camera couldn't focus down enough to take a nice shot. I've taken the liberty of drawing a few labels on in case you have trouble spotting them. Click to see a bigger pic.
In this final shot the sea fan's feeding tentacles are out so you can see what the red bumps are and the pygmy is looking straight at the camera so you can only see his tube snout and a fat little belly (which I think may harbour some eggs (male seahorses hold the eggs)).