Rob Toonen, and invertebrate zoologist, wrote an excellent article on flame scallops. Note that they don't have a long life span, but it is longer than a year in the wild.
Just in case that didn’t sink in, I wanted to make a point of emphasizing that the survival record of flame scallops in captivity has traditionally been extremely poor. The typical experience of people who buy them is that the animal tries its best at hiding (often with the aquarist having to pick it out of the rockwork numerous times so that it is visible in the aquarium) for a while before eventually giving up and slowly dying. Even when the rest of the reef tank is flourishing, people who add a flame scallop to their tank typically watch as it slowly wastes away over a period as short as a couple of months to a maximum of about six to ten months. I would guess that the single most common cause for the demise of flame scallops in any aquarium is quite simply starvation. Although I should also point out right off the bat that these animals are relatively short-lived (something on the order of about three to four years maximum, and I’ll come back to this later), there are still precious few reports of these animals surviving in captivity for more than a year or so. Sadly, the 6-10 months that most people manage to keep a flame scallop in their tank is also a reasonable estimate of how long it should take a well-fed animal to starve to death after collection and being placed in an aquarium in which it is deprived of food.
It is critical to feed these guys appropriate size food...and just because they appear to injest it, does not mean they are EATING it.
If, however, you are not feeding mixed phytoplankton and zooplankton of the appropriate size on a regular (and by this I really mean at least daily) basis, adding a flame scallop to your aquarium is quite simply a death sentence for the animal, because it is going to starve to death. If that is the case, then no matter how cool you think the animal is, you should not add one to your aquarium.
Also keep in mind that they will often hide behind rockwork. They can move, and rarely can be "placed" where you want to see them. Under no circumstances, IMO, should they be moved as this can damage the animal.