......that can make a dive special. I was diving an artificial reef called Theo's Wreck when I found the nudibranch below, Thuridilla picta, as I peered though a porthole. The reason the picture below is a bit grotty is that its a tight crop as this nudi is less than 5mm long. Even with my inon macro lens I couldn't get a clear shot due to the shape of the wreck. I always get a sense of immense satisfaction when I find something this small. It reminds us just how complicated the underwater ecosystem is and how many unique species there are. Over at digitaldiver.net divers produce tiny critters in the identification forum and its amazing the number of times the answer comes back this is a new or undescribed species. This little chap is well known and well travelled though - known from warm water on both atlantic coasts -he'll eventually reach about half an inch.
Above is the full frame (with an arrow to help you spot him). When you consider the different polyps and algaes also visible in this one tiny patch you can see how we have fun on a 200 foot wreck.