Terracotta Octopus Pots? What the heck?

Terracotta Octopus Pots?  What the heck?
Pulpo a la gallega is very famous in Spain.  Pulpo is octopus and "a la gallega" refers to how the octopus is prepared for eating.  Basically, there is a necessary procedure for cooking octopus so that it does not become rubbery to eat.  The cooking to tender is the most important...