LionFish says.....
Man, your tusk sure does some wierd stuff. I have seen mine do this but he is fine for all I know because he wasn't breathing hard and was showing no sign of diseases. I guess the tusk just likes to sit down and relax for a minute or 2. Is he showing signs of stress or disease right now? Is he breathing hard? If not, he may just like to sit there for a while. Tusks are known to sit in the sand from time to time. It doesn't sound like too much to worry about but if he isn't diseased or breathing hard, there shouldn't be anything to woory about. Keep me updated.