Have 2 1-feet tanks, one with small pebbles stones ( tank n pebbles are more than 6 years old ) and an almost 1 year old tank with fine black sand.
Can see they enjoy digging around the sand to create their own crevices.
They even bred once in the pebbles tank.
Come to think of it, my L46 are more than 6 years old now. Wonder how long they can live? The biggest one is super duper fat..