Was that a snap crackle or pop?

[Zerandise]

First let me say

I love my wife.

So me and my wife are sitting on our computers doing our thing. Her desk is about 2 feet from my 140g tank. We are having some nice happy quiet time when she perks her ear toward my tank and says " That is the oddest sound lover...". I look up at her and ask that sound it is. Her innocent reply is " snapping/popping sound your tank makes". Come to find out a couple weeks before she had started to hear this snapping noise on one end of my tank. she would hear it nightly. We work opposite hours so she is near my tank when lights are off and all is calm, or so i had thought.

She asked if a popping noise is a back thing! Im sure now after a week of listening to it that its just a pistal shrimp. My jaw sure did drop tho at those first few pops... A mantis inan invert tank would not be a good thing!!!!