Resembling an oversized egg in a nest, the Tij (or Tide) is a bird observatory in the Netherlands designed by Dutch firm RAU Architects. The novel building is made from sustainably-sourced wood and can be disassembled and moved with relative ease if required.

The recently-completed project, which also included Ro&Ad Architects and HNS Landscape Architects, is located at the Haringvliet, a North Sea inlet in South Holland. The area was previously dammed due to flooding but has been reopened to the sea in an attempt to restore its ecosystem.

Tij measures 120 sq m (almost 1,300 sq ft) and is accessed through a sand-covered tunnel made from recycled stone bulkheads. This ensures the local bird life isn't spooked by people coming and going.

The prefabricated building was delivered by boat in roughly 400 pieces and assembled on site. The bottom part comprises accoya wood beams, which will not be damaged if submerged in seawater due to high tide. The upper part is made from pine and covered in locally-sourced reeds.

"Thanks to its complete rebuilding capabilities, modularity and materialization, it fully meets all the key points for a sustainable structure with circular potential," says Thomas Rau, chief architect. "By building everything in such a way that everything can be taken apart without losing any of its value, we ensure that the strain on the ecosystem is minimal. The shape of the observatory is extra special, mimicking the egg of the large tern. Nature itself produced this shape."

Tij is the latest in a line of egg-shaped architecture projects we've covered, including a sauna, an artist residency, and a tiny house.

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