Ceramic Aquarium Shrimp Shelter - Cylindrical Part # 11889-01
 
Size Approx - 3.75 cm x 3.75 cm x 7 cm  / 2.75" D x 1.5" W x 1.5" H
Provides refuge and protection from predators
Can provide substrate for fine algae or bio-film
Seclusion for molting / female with eggs