Something clicked. I've been crabbing and cooking & eating crabs since I was old enough to drag a basket in an innertube with a dipnet and walking through the seagrasses catching them. (eventually as I got older then used a boat with trotlines about half a km long. Anyway, depending on where you grew up in crab territory different things have different local names or references. So, dwelling on this for a while I think I might have figured out what is being referenced here.
If you take a crab that is within, say, one week of molting (shedding its shell and becomes the real delicacy for the crab aficionado for a couple of hours before the new shell hardens - normally called a softcrab
), when you pull off the top shell there will be a soft shell inside the hardshell. If the crab is boiled or steamed (my style) whole then when you pulled off the shell the soft shell is there inside the hard top shell and is excellent eating. Having said that when you cook a crab you will notice the colour change of the topshell from green to a reddish-brownish colour. Well, the inner soft topshell also turns the same colour as it has the same colour characteristics as the shell it would have replaced. The is probably the brownish meat that our OP is referring to.
Steamed Mangrove Crabs (local chilicrab crab) and the way we eat them at home (cannot afford to to this here all that often as we can demolish about 2 dozen at one sitting (between me & Son & Daughter) When we do it, we usually go out to Senoko to the Wharves and buy direct from the middleman but still rather expensive as we don't eat anything else but crabs and maybe cubes of cheddar cheese, some Corn on the cob and beer! (not the kids though, back then. (Daughter was 15 or 16 in pic).