"Nudibranch literally means 'naked gills'. The feathery growths sprouting from their back are just that," explains Nathan Hill in the October 2010 issue of Practical Fishkeeping.
The nudibranch is a stunning and highly specialised life form, but as Nathan explains in this special feature, for many reasons the hobby isn't ready for them yet.
Find out more about these beautiful creatures in the October issue, along with the reasons why the term 'sea slug' is so misleading, the reasons not to buy them for your reef tank – and why even dead specimens should be handled with care!
The October issue is on sale from September 1, 2010.