So, if i wanted to put some shells that I brought back from Jamaica in my tank, I should scrub them and boil them first?

Ok, not to be technical, but salt water shells are not recommended in a freshwater tank -- or really any kind of shell. This has to do with chemistry. Shells not only change the ph but also water hardness. if you have been keeping shells in your aquarium for decades Asa some claim, then you are doing aware checks and correcting for the problems shells create. geneerlly, to correct hardness, you have to change a portion of the water weekly. If you don't, we'll your fish may be surviving but they are less than healthy and subject to disease.

Now I realize this is the age of the Internet and no one reads anything longer than 5 sentences, but ad the aquiirm bibles ie, Alexrod's Mini Atlas and Inness' Exotic aquarium fishes. After all, they are the experts -- and if you don' t know who they are, they are influential enough to have fish speck named after them.