This is more of a traditional ceramic cave that does not have any natural textures. 
These pleco caves from Pleco Ceramics are made from brow clay fired at high temperatures. This makes the pleco cave absolutely safe for people, aquarium fish and pets. The cave can be used for breeding many kinds of plecos such as Ancistrus (Bristlenose pleco), Hypancistrus and Peckoltia. 
Dimensions are selected based on their 10-year experience in breeding plecos. A great bit of detail is put into every cave. 
These caves can also be used for shelter for many cichlids and shrimp!