Once in a while when I'm thawing and prepping frozen shrimp, I'll come across one that's quite a bit softer than the others. The flesh is a bit floppy and not firm like the others, and even the shell seems thinner and flexible. Other things like size, color, and smell are all fine. Is there anything wrong with these shrimp? Maybe they were sick or malnourished in life? They seem to be fine after cooking, indistinguishable from the rest.