Coccolithophore shells Many protists have protective shells or tests, usually made from silica (glass) or calcium carbonate (chalk). Protists are a diverse...

A protist (/ˈproʊtɪst/ PROH-tist) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural...

Marine protists Marine protists are defined by their habitat as protists that live in marine environments, that is, in the saltwater of seas or oceans...

organic–inorganic composite material produced by some molluscs as an inner shell layer. It is also the material of which pearls are composed. It is strong...

In biology, a test is the hard shell of some spherical marine animals and protists, notably sea urchins and microorganisms such as testate foraminiferans...

hardened secretion of stony corals and the prominent mollusc shell shared by snails, clams, tusk shells, chitons and nautilus. Some vertebrate animals, such as...

A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer usually created by an animal or organism that lives in the sea...

Diatomaceous earth consists of the fossilized remains of diatoms, a type of hard-shelled microalgae, that have accumulated over millions of years. It is used as...

in biological systems, such as the formation of stromatolites or mollusc shells (see Biomineralization). Calcification can manifest itself in many ways...

The mollusc (or mollusk) shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca...

as cuttlefish bone, is a hard, brittle internal structure (an internal shell) found in all members of the family Sepiidae, commonly known as cuttlefish...

and cuttlefish) have an internalized vestigial aragonite/calcite-chitin shell known as gladius or cuttlebone, which can serve as muscle attachments but...

(shells) Arthropod exoskeleton cuticle Brachiopod shell Cephalopod shell cirrate shell cuttlebone gladius Lorica Choanoflagellate lorica Protist shell...

another example, many fossil genera of Foraminifera, which are protists are known from shells (called tests) that were as big as coins, such as the genus...

predator to utilise the organic content of coccolithophores. Heterotrophic protists are able to selectively choose prey on the basis of its size or shape and...

(shells) Arthropod exoskeleton cuticle Brachiopod shell Cephalopod shell cirrate shell cuttlebone gladius Lorica Choanoflagellate lorica Protist shell...

class of Rhizarian protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an external shell (called a "test")...

as support, defense, and feeding. Many protists, like this coccolithophore, have protective mineralised shells. Forams from a beach Many invertebrate...

(or shells) of Foraminifera. Foraminifera (forams for short) are single-celled predatory protists, mostly marine, and usually protected with shells. These...

The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical...

predator to utilise the organic content of coccolithophores. Heterotrophic protists are able to selectively choose prey on the basis of its size or shape and...

silicate shells. Phytoplankton that build calcium-carbonate shells (i.e. coccolithophores) release carbon dioxide as a byproduct during shell formation...

shells. These animals may have been molluscs or worm-like Sipuncula. Other molluscan univalved shells have been found in Canada. Some bivalve shells have...

(shells) Arthropod exoskeleton cuticle Brachiopod shell Cephalopod shell cirrate shell cuttlebone gladius Lorica Choanoflagellate lorica Protist shell...

are no longer classified together in one group. The best known amoeboid protists are Chaos carolinense and Amoeba proteus, both of which have been widely...

development of the larval shell, but not the adult conch (a separate entity), suggesting a different evolutionary origin of the mature shell. In cephalopods, engrailed...

fluids seep into the voids of Earth materials, e.g., rocks, wood, bones, shells, and replace the original materials with silica (SiO2). Silica is a naturally...

(shells) Arthropod exoskeleton cuticle Brachiopod shell Cephalopod shell cirrate shell cuttlebone gladius Lorica Choanoflagellate lorica Protist shell...

(shells) Arthropod exoskeleton cuticle Brachiopod shell Cephalopod shell cirrate shell cuttlebone gladius Lorica Choanoflagellate lorica Protist shell...

functional biominerals, such as endoskeletons and exoskeletons, protective shells, or teeth, had been a significant step in animal evolution. Calcium carbonate...