Alex can you say anything more about the dive site. The one I found was in the Marsa Alam area, Marsa Shagra, in about 2m depth. Its tube hole was in a dead limestone block facing the sandy chute leading from the beach out through the reef. I will be back in the Red Sea this May and would love to see and study it better.
Of course. The one in my photo was at a very similar depth. At Gubal Island at the mouth of the Gulf of Suez in the Strait of Gubal. The little guy was also in a hole in a non-living coral rock, in a small lagoon between the fringing reef and the land.
If you know the barge dive site, you swim in shore and through a shallow cut in the reef to the lagoon. Ahead of you, after you arrive in the lagoon, there is a large branching hard coral, which I call the lemon tree because it is always filled with lemon gobies and surrounded by sand is a great place to photograph them. This rhino - unicorn blenny was on past the lemon tree on the inside edge of the lagoon.
Knew it was strange when I shot it (and actually borrowed a friend's SMC close up lens to shoot it), but then didn't think any more and went back to shooting more regular subjects.