How do i know the clicking sound is from pistol shrimp or mantis? i cannot see it, just it's feedle when i shine light in its hole. There is once when my sand shifing goby tries to use the same hole as it home, i heard a click sound and the goby darted out. I have another pistol and randell goby pair but have never heard it click, just can see it busy at work pushing out all the sand.