Ceramic Aquarium Shrimp Shelter - Tall House Part # 12121-03
 
Size Approx - 3.8cm D x 4cm W x 9cm H  /  1.75" D x 1.75" W x 3.75" H
Provides refuge and protection from predators
Can provide substrate for fine algae or bio-film
Seclusion for molting / female with eggs