Geo Monumentos

A little known and rarely visited Lisbon historic site is the Geo Monumentos, in the city's Campo Ourique district. This is the remains of a chunk of coastline that dates back to at least 20 million years to the Miocene period â€" a rare example of where a much warmer and far cleaner ocean met the land, and where a shallow reef was created. As the ocean receded over millennia the once submerged reef was exposed to reveal the fossilized remains of bryozoan colonies. Bryozoa are filter feeding aquatic invertebrate animals that sieve food particles out of the water using a crown of tentacles. Layers upon layers of the skeletal fragments of these minuscule marine creatures gradually built up to create what we see today, a piece of ancient coastline that's set many kilometers inland and at a much greater elevation from Portugal's present Atlantic Ocean coast.