[ te-stey-shuh n ]
/ tɛˈsteɪ ʃən /

adjective Zoology.

having a shell or test.

Origin of testacean

1835–45; < Latin testāce(us) shell-covered, testaceous + -an
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Science definitions for testacean

[ tĕ-stāshən ]

Any of various protozoans of the order Arcellinida (or Testacida) that are encased in a shell. Testaceans are rhizopods and are related to amoebas. Their shell usually has one chamber and may be secreted by the organism as a chitinous or siliceous covering, or may be glued together out of sand particles.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.