Pupa kirki is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of small sea snail, a marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 gastropod mollusc in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Acteonidae

Acteonidae

Acteonidae, common name the "barrel bubble snails", is a family of small sea snails, marine gastropod mollusks of the informal group Lower Heterobranchia.-Shell description:The shell is usually smaller than 25 mm...

. It is found in the waters around the North Island

North Island

The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...

 of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

.

The length is 15 mm.
The shell is usually white, beige, or brown, with or without black markings, and is egg shaped (ovate) with an elevated spire

Spire (mollusc)

A spire is a descriptive term for part of the coiled shell of mollusks. The word is a convenient aid in describing shells, but it does not refer to a very precise part of shell anatomy: the spire consists of all of the whorls except for the body whorl...

. The columella or central axis of the shell has a large double fold.

The species, described for science by Frederick Wollaston Hutton

Frederick Wollaston Hutton

Captain Frederick Wollaston Hutton, FRS, was an English scientist who applied the theory of natural selection to explain the origins and nature of the natural history of New Zealand.- Biography :...

, may have been named for New Zealand cephalopod biologist Thomas William Kirk

Thomas William Kirk

Thomas William Kirk was a biologist, scientific administrator from New Zealand. He studied the fauna and flora of New Zealand.He named various taxa of New Zealand molluscs including:* Cylichna zelandica T.W. Kirk, 1880...

, or his father Thomas Kirk, curator of the Auckland Museum.