The blenny comes out to "defend his area" from an intruder.
The intruder is his image in a small mirror. The bright shallow water allowed for
a ISO 100, f/16, 1/160 shot, with the Canon 5D and a 100mm macro lens.
They usually do not come completely out of their hole. This fellow came out
and circled the mirror trying to find the intruder.
click on pic for larger version