They are most likely getting used to their surroundings, and probably just foraging for food. Give them a week or so and i'm sure you will begin to see them going all over the place in search for food.
Also, a larger picture of that thing in the sand would definitely be a good idea because you can hardly see what it is in that thumbnail.. plus it's basically the color of the sand which doesn't make it any easier to identify lol. Right now.. judging by the fact that it does look sort of like a tube.. i'm going to input a feather duster, but i don't think we can really pinpoint what it is exactly without a larger more detailed picture.