Date approximate only(definitely mid to late autumn, and I am 99 %sure re year but if not 1991 then 1990).Scuba dive under jetty. Depth about 4m. Crab was on a lower flatter part of same very large composite red sponge in a spot that prevented decent imaging so I moved it gently onto taller more open part of same sponge. Then returned it to where found.(This jetty is 'sponge central station' WRT diveable SA jetties)