It is very easy to see why this creature is called the “hunchback,” for although when it is quite small it is shaped just like other scallops, it alters in form very much as it grows bigger; so that really it sometimes looks as if it had been crumpled up when it was quite soft, and had never recovered from the squeeze. Besides this, the two valves are not alike, as they are in other scallops, for while one is always very deep and rounded, the other is nearly flat. So when the animal is alive it really has a kind of “hunchbacked” appearance; and if you found its two valves lying apart from one another you would hardly believe that they could both have belonged to the same creature.
The colour of the hunchbacked scallop is white, mottled with brick-red.
This is a very “local” shell. That is, it is very common indeed in some places, so that you might pick up hundreds and hundreds in a few minutes, while in other places it is never found at all. The best place in which to look for it is a part of the beach where sand and mud are mingled together, and there you will be almost sure to find it.
The name of “sunset” shell has been given to it because of the beautiful way in which the inside surface is coloured. Sometimes it is rosy pink all over; sometimes it is orange yellow; sometimes it has crimson streaks upon a whitish ground. But you can never look at it without being reminded of the evening sky after a very bright sunset. The outside of the shell, however, is always white and chalky-looking, and no one who saw the two valves fastened together as they are when the animal is alive would have the least idea how beautiful they really are.
This creature always lives buried in the sandy mud, just as the cockle does. It has a very powerful “foot,” by means of which it burrows, and two long and very slender siphon tubes.
This is another of the shell-bearing molluscs which live in burrows in the sandy mud, and it is called the “gaper” because the shells are always open at the top, just as if the animal were yawning, or gaping. Through this opening the siphon tubes project. These tubes are used in breathing, just like those of the cuttle, and are enclosed in a kind of leathery case, which the animal can stretch out or draw back at will; so that when it is lying at the bottom of its burrow it can keep the tips of the siphon tubes just above the surface of the mud, and so draw water down to its gills quite easily.