Articulated Sand Shrimp.
Although it looks mega poofy, it slims down on the move- which is tough to capture in a still image. So it looks bulkier than it fishes. That said it's still going to be somewhat of a burden to cast, but made good use of the ultra-fluffy parts of saddle hackles that aren't typically used for much.
Supposed to be a female with eggs, but with sand shrimp the sky's the limit on what colors to tie. Typically the ones I see are a rosy pink or orange with a white head and legs, so I matched that as best I could.
I've got a few beaches in mind with large mud flats closeby and huge numbers of shrimp. If nothing else it will be hilarious watching this giant shrimp creep back on the retrieve. Fly-watching is definitely an underrated aspect of streamer fishing