Description

Sundial shells are rather unique in being markedly flattened and in showing a lenticular edgewise appearance. Ever-widening whorls leave a deep umbilicus open to the tip of the spire, showing a beautifully detailed banding pattern that is reminiscent of a spiral staircase. The operculum is beehive shaped and chitonous (horny) rather than calcareous.

Shallow sands are normal habitat, and the mollusc is fairly widely distributed in warmer waters of the West and East coasts of North and South America, as well as Indo-Pacific regions.

Comparing principal genera,  Architectonica shells are distinctively flattened sundials, whereas Heliacus shells have a wider aperture opening to the side. The operculum is also different in having a several turn chitonous spiral. Philippia are found on sea anemones and other cnidarians, on which the snail typically feeds.

 

Classification

Class: Gastropoda

Clade: Heterobranchia

Superfamily:Architectonicoidea

Family: Architectonicidae

 

Major Genera

• Genus: Architectonica
• Genus: Heliacus
• Genus: Philippia

Architectonica maxima (Philippi, 1849)
Giant Sundial