Thanks Steve and Alex.
Yeah, good point about taking flack and it was something I should have addressed in my initial comment.
During my trip I had six mimic sightings (it was a very lucky trip). The first four times the mimics acted a particular way. When they were moving around they 'impersonated a sole'. See image below...

However on my penultimate day of diving we found a mimic that acted differently. It travelled head first. See image below.

However after travelling head first for a little bit it then bolted up off the bottom about 5 metres off the sand. It then stopped and then 'impersonated a feather star' as it drifted back down to the bottom. On the final day, I took out my 10.5mm in the hope of finding a mimic or something to get some slightly different perspectives. Fortunately we found the same mimic as the day before. Again it acted the same way, travelling head first and then bolting up off the bottom etc. Both times it leapt off the bottom on its own accord which apparently is very rare so it was a real privilege to experience it twice! Scouts honour! 
PS Alex, we actually came across an inflated pufferfish on a night dive as well. 