I doubt you are nearly as bored as a Hermit Crab purposely filling shells with gravel...
Seriously, last night I dumped it out... Then this afternoon I watched him for a good hour pushing gravel into shells... I think he is telling me he does not want them in the tank anymore. He usually eats the shells instead when he doesn't want them.
Shell Full Of Gravel
Bonus "Pizza Is Awesome" Pic - "This is what distracted him from his super-important shell-filling venture; Guess Hermit Crabs take lunch breaks too..."
