Shrimp #3... why is this so confusing?

So my shrimp are doing their darnedest to make me believe that I have gone insane.  First I went a long period of time thinking that one had died and I only had 2 left.  Then I saw 3 swimming around a month later and was elated/shocked.  Yesterday I saw only 2 and thought that maybe I was insane about ever seeing the 3.  So I looked and I looked and eventually I saw some red.  I shook the container some more so I could see the red more clearly and got some photographic evidence.  Shrimp #3 is in the mouth of a snail shell.  I have never known the snails to be alive, and I thought the shell was just decorative, so I can't say for certain whether the shrimp is alive and hiding in the shell or dead and being eaten by a snail I was not aware I had.  But I can now firmly state that I did have 3 shrimp in my ecosphere.  Even if I might be a little crazy, I am indeed still capable of counting shrimp in a small glass egg.