Review on Penn Plax Replicas Aquarium Hide Away RR1076 by Steven Ripley

They are made of sand bonded with a type of resin. We added the largest cube to our aquarium by placing it on a sandy base. About a week later we decided to replace it with a medium sized cube and when we removed the large cube it gave off a strong, horrible smell of sulfur and burnt plastic. The white sand he sat on turned a sickly blue-grey. When we shoveled out the affected sand, it also smelled like plastic. I will let you know if we have any problems with livestock in the tank but I would never put them in the tank again. It's just disgusting :(