Missing Pistol Shrimp, Molting perhaps?

[PiscesPower]

I have a very active pistol shrimp paired with an orange spotted goby. He was redoing my sandscape last night before I sent to bed. This morning nowhere to be found, and his goby is out in the open. I did notice these suspiciously molted antennae lodged on a coral and the goby seems to be guarding the. I do have 2 cleaner shrimp as well so the molted antennae could be from one of them

Would it be common for the goby to guard a piece of the molt? and Does the shrimp hide to molt? and finally How long does a molt take?

Crappy pic sorry, but you can see the antennae on the coral to the right of the fish, its like a Y that got caught on the coral (I will remove it later).

 

[Hilltop Aquariums]

When my mantis shrimp molts she will block the entrance to her cave and stay there for about a week. She won't even come out to eat.