page_title: Thrombolite
hierarchical_section_title: Thrombolite
caption_attribution_description: English: Purbeck Formation thrombolites, Isle of Portland, Dorset, England.
context_page_description: Thrombolites are ancient forms of microbial communities that can be either photosynthetic or heterotrophic. They are clotted accretionary structures formed in shallow water by the trapping, binding, and cementation of sedimentary grains by biofilms of microorganisms, especially cyanobacteria. They are now only found in a few places in the world. Stromatolites are similar but consist of layered accretions. The ancestors of thrombolites and stromatolites are thought to have contributed to the increase in oxygen in Earth's atmosphere.
context_section_description: Thrombolites are ancient forms of microbial communities that can be either photosynthetic or heterotrophic. They are clotted accretionary structures formed in shallow water by the trapping, binding, and cementation of sedimentary grains by biofilms of microorganisms, especially cyanobacteria. They are now only found in a few places in the world. Stromatolites are similar but consist of layered accretions. The ancestors of thrombolites and stromatolites are thought to have contributed to the increase in oxygen in Earth's atmosphere.
caption: Jurassic thrombolite formed around a tree trunk; Purbeck Formation, Isle of Portland, Dorset, England.
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