Mystery from below

[dsaundry]

Ok, I am looking through my tank last night and I see what appears to be a sausage-like casing with 2 antenna sticking out of it.{will try to get pics later} There is no creature in it but initially I am thinking Bristleworm? I don't see any other issues with corals or fish so I am thinking all ok for the most part. I am checking my e-mails and I hear three small snap sounds. I then think Pistol Shrimp?? But I do have a Pistol in my small tank at work and these insect shaped casings are far bigger than my little guy at work. The other thing I don't see is mounds of sand moved around as my Pistol at work does. Any suggestions and although I don't see any damage to corals or lifestock am I playing with fire? Has anybody else seen these things in their tank? As I said I will try to get pic's this evening when I get home.