My new plants came in today so there are more places for Snack to hide. He is not shy at all though and usually stays visible. He didn't even hide while I was planting. Chips was less interested in him today, but I purchased 2 more bushy-type plants and some moss just in case. I can't get out to the store to get him another friend until Saturday.
At this point I believe the munched shrimp was the victim of a failed molt, and my Betta took advantage of it.
I had lots of hermit crabs and a few shrimp in my reef tank, and the shrimp and fish would leave the hermits alone until they molted and then it was buffet time. I also had one Banded Coral Shrimp that lived for years until one night he picked a bad hiding place to molt. They always disappeared completely into the live rock tunnels when they molted. I was there watching him, and right before he got out of his old shell, one of my fish tore across the tank and cut him in two. My other fish (and both my Cleaner Shrimp) joined in and he was gone in minutes. I was rather fond of him, but omg don't molt out in the open.