The reef-builder invertebrate collections concern various organisms able to create underwater reliefs on a macroscopic scale.


Presentation
Most organisms referred as reef-builder invertebrates secrete a mineralised skeleton, mainly made of calcium carbonate, sometimes very thick, and may display a colonial behaviour. The binding, agglomeration and covering of these mineral secretions lead to the formation of bioconstructions. On a planetary scale, the coral reefs are a good example of this type of process. The reef-builder invertebrate collections mainly include quite simple life forms (porifers, cnidarians), represented by whole skeletons as well as supporting elements of the skeleton like spicules. Today, there seems to be a consensus that fossil groups with long-discussed systematic affinities should be included among the porifers, alongside siliceous and calcareous sponges. These include archaeocyaths, chaetetids and stromatoporoids, which might thus simply represent various types of organisation. However, corals (Cnidaria, Anthozoa) better characterise the notion of reef-builder organisms. They are particularly well represented in the collections, with around tens of thousands of specimens (including thin slides) from which 4,300 types or figured specimens.

History
As with all the museum collections, the rich and varied nature of the collections assembled here greatly depends on the research work carried out over the years, particularly at the Muséum. Since the creation of the historical coral collections in the 19th century (Michelin, de Fromentel, Milne Edwards, Ferry, etc.), which are essential reference points for systematic studies, they have been constantly enriched by the extensive work of researchers affiliated with the Muséum (Alloiteau, Chevallier, Beauvais, Gill, Lafuste, Sémenoff, Chaix, etc.). Among porifers, the archaeocyaths constitute the most significant collection at the Muséum, with Cambrian specimens from all over the world. Resulting mainly of the Françoise Debrenne researches at the Muséum it is one of the world’s biggest collections, rich of 600 types and figured specimens. A website dedicated to them was created by Adeline Kerner: www.infosyslab.fr/archaeocyatha.

Research
The reef-builder invertebrates collections are supplied by donations, bequests and purchases, as well as items sampled during field researches, almost as part of the Muséum’s own programmes. They are available for fundamental research in systematics, palaeoecology and palaeobiogeography. The material and information have been used by researchers from all over the world, either through visits or loans, and have also been an aid to many authors of published works.