The distinctive aroma of...

So I noticed a bad smell in my house last week. Once I noticed it and the hours passed by it seemed to get worse and worse. I searched high and low but couldn't locate where it was coming from, partly because it was so bad it was hard to smell without heaving, in order to find it. I figured it was a dead mouse or rat since I had recently seen one and put out traps and poison. The poison is supposed to make them thirsty, so they go outside, then kill them. I was really hoping there wasn't a dead rat in my roof or wall. Anyway the next day the power happened to go off and I was home when it came back on. Just as it did I walked into the kitchen and boom, like a wave the smell hit me. It was clear it was coming from the back of the refrigerator. The fan on the back, now on, was sending the smell out right at the entrance to the kitchen. So I took the back off and searched around with my flashlight but found nothing. I called the landlord and the next day she sent a guy over who couldn't find anything either. So two days later they all came over with another guy. This time they really got deep inside the back and low and behold found the rotting, maggot filed shell of a former crab. Now how the hell did a crab get in the back of the fridge?