Illustration of radiolarian
radiolarian
noun
ra·di·o·lar·i·an
ˌrā-dē-ō-ˈler-ē-ən 
: any of three classes (Acantharia, Polycystina, and Phaeodaria) of usually spherical chiefly planktonic marine protozoans having radiating threadlike pseudopodia and often a siliceous skeleton of spicules
radiolarian
adjective
Examples of radiolarian in a Sentence
Recent Examples on the Web
The images were captured from SEM scans Benson took over the course of six years at the Canadian Museum of Nature in Quebec, including radiolarians, dinoflagellates, and diatoms, as well as multiple types of insects, microscopic flowers, and even lunar samples obtained from Apollo 16.
—
Jeff Spry, Space.com, 22 Dec. 2025
After which radiolarians sink, producing a steady snowfall of delicate glasswork onto the ocean floor.
—Literary Hub, 28 Oct. 2025
At left, a large Thalassicolanucleata radiolarian with a central capsule enclosing the nucleus.
—Discover Magazine, 3 June 2015
The organic carbon decline coincided with the disappearance of more than 50 species of radiolarians, which served as a food source for numerous marine species and whose disappearance was an indicator of a major biological crisis.
—Reuters, WIRED, 10 May 2001
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Jeff Spry, Space.com, 22 Dec. 2025
After which radiolarians sink, producing a steady snowfall of delicate glasswork onto the ocean floor.
—Literary Hub, 28 Oct. 2025
At left, a large Thalassicolanucleata radiolarian with a central capsule enclosing the nucleus.
—Discover Magazine, 3 June 2015
The organic carbon decline coincided with the disappearance of more than 50 species of radiolarians, which served as a food source for numerous marine species and whose disappearance was an indicator of a major biological crisis.
—Reuters, WIRED, 10 May 2001
Cite this Entry
“Radiolarian.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radiolarian. Accessed 31 Dec. 2025.
Copy CitationKids Definition
radiolarian
noun
ra·di·o·lar·i·an
ˌrād-ē-ō-ˈlar-ē-ən
-ˈler-
: any of various usually ball-shaped marine protozoans that have small spines radiating from the shell and have a skeleton containing silica
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