2" is a pretty good size for ghost shrimp. They might be M. lanchesteri (which looks ofter like a glorified ghostie). They are more like a dwarf macro. If it doesn't have a red rostrum, it's definitely not a giant prawn (which often get muddled up in the trade as ghost shrimp). Judging by how little it has grown, I'm almost positive it isn't a larger species.
Pic of lanchesteri:
HTH
Pic of lanchesteri:
HTH
