As above the OBT has been off food for a few weeks and from the tiny window into the burrow I can make out part of an upside-down leg looking all brittle and a much larger leg stood the right way up. Such is the way of these though I'll have to wait until they harden and clean out the burrow before I get any confirmation of this but early signs are good. Now I have an even bigger OBT to deal with. Good job I love them.
When they are little they almost double in size each moult but as they get older it wont be quite so much. My Salmon Pink doubled in size the same night I got her and she is ready to moult again I will try get a measurement photograph with something for scale but it wont be easy she has created an epic labrynth of a burrow.