Atlantic casmaria

About this species

Casmaria ponderosa, common name the heavy bonnet, is a species of large sea snail, a marine gastropod mollusk in the family Cassidae, the helmet snails and bonnet snails.

Text from the Wikipedia article “Casmaria ponderosa”, licensed CC BY-SA 4.0. Read the article

Where and when

Where it has been recorded

Worldwide

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Best months

Worldwide (open data)

January: 9 records
February: 13 records
March: 8 records
April: 17 records
May: 17 records
June: 38 records
July: 19 records
August: 17 records
September: 15 records
October: 12 records
November: 10 records
December: 9 records

Depth and water temperature

Depth

Mostly recorded at 21–160 m · Deepest record: 557 m

0–10 m: 1 records
10–20 m: 2 records
20–30 m: 1 records
30–40 m: 2 records
40–50 m: 8 records
50–60 m: 16 records
60–70 m: 1 records
70–80 m: 0 records
80–90 m: 1 records
90–100 m: 0 records
100–110 m: 0 records
110+ m: 4 records

Water temperature

Recorded in surface water of 20–30 °C

20–22 °C: 10 records
22–24 °C: 27 records
24–26 °C: 51 records
26–28 °C: 55 records
28–30 °C: 67 records

Photos

(c) H. Zell, some rights reserved (CC BY-SA) · CC BY-SA · iNaturalist
(c) Lisa Bennett, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Takaaki Hattori, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Eugene Popov, some rights reserved (CC BY) · CC BY · iNaturalist

Names and classification

English: Atlantic casmaria, Heavy Bonnet, Heavy Bonnet Snail

Names in 1 more languages

Japanese: アメガイ

Other scientific names: Buccinum biarmatum, Buccinum nodulosum, Buccinum pantherina, Buccinum ponderosum, Cassis tenuilabris, Cassis torquata, Phalium ponderosa, Phalium ponderosum, Phalium quadratum, Phalium torquatum

Similar species

Sources and credits

Names and taxonomy: WoRMS (CC BY 4.0) and the GBIF Backbone (CC BY 4.0). Photos: iNaturalist observers, each under the licence shown (CC0, CC BY or CC BY-SA).

Depth, temperature, months and maps: records from OBIS and GBIF under CC0 or CC BY.
Descriptions: Wikipedia, licensed CC BY-SA, each linked to its article.
Conservation status as published by GBIF (IUCN Red List).
497 open-data records from 1791 to 2012.
Species data updated October 26, 2026.