Subject @ centre could be mature or could be a young specimen of a larger taxon such as H. grandis;I'm not sure. I only noticed a few f the imaged type,on a 2+1/2 hour leisurely dive,mostly spent under mid section of old jetty,during which I spent much time scrutinising sessile invertebrate growths (and algae) as well as the usual mobile inverts and bony fishes.Outgoing tide,modest,throughout dive.My 2 buddies used their first tanks up halfway through my bottom time and were re-entering at new jetty platform as I exited.
[An aside:Small vital lung capacity(?associated with small brain?...lol) has one outstanding advantage:I spend less on air refills than most divers I know! One disadvantage being that in the cool season I often get cold after say 60-90 minutes,and often exit with half a tank un-used,which for safety on next dive needs refilling anyway]

NOTE If anybody on iNat has wondered why they've lately noticed an increase in my personal dive info 'clutter and boredom index',its because I've decided to rely mainly on iNat as a de-facto personal Dive (and where camera used,Snorkel) Log Book.Seems perfectly reasonable,an easy way to briefly record ecological points of relevance e.g. proportion of rock reef vs sea-grass meadows,or seasonally over fluctuations in algal cover.(Obviously, by not including details irrelevant to the marine life seen on dives or snorkels,but required in proper dive logs,e.g.name of buddy,signature(s),tank air pressure readings at start and end of dives,I'm not able to use iNat as an actual Dive Log acceptable to charter operators,etc. I still need to keep those details separately in my hard copy log books).