of outrageous fortune....Some crustaceans can be a real problem to photograph. Using the wetmate macro lenses reduces depth of field considerably which isn't a problem until you come across something like this arrow crab. With appendages and probiscuses and things poking out all over the place its near impossible to get the whole thing in focus so I tend to aim for the eye/mandibles/head bits.
This arrowcrab was one of many sharing Theo's wreck with a lot of fireworms. I know in aquaria arrow crabs have a reputation for tucking into problem bristleworms but whether or not they'll have a pop at the fireworms or whether the large numbers of each was a coincidence I don't know.