Bluish Top Shell

Diloma nigerrimum

Molluscs
IUCN: Not evaluated

Usual depth0–8 m
Water temperature5–28 °C
Best monthsApril, June, and December
How commonRare

All species

Photo credit: (c) Lisa Bennett, some rights reserved (CC BY), uploaded by Lisa Bennett · CC BY · iNaturalist

About this species

The bluish top shell is a species of small sea snail, a marine gastropod, in the family Trochidae, the top snails.

Text from the Wikipedia article “Diloma nigerrimum”, 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: 21 records
February: 14 records
March: 14 records
April: 28 records
May: 10 records
June: 31 records
July: 25 records
August: 17 records
September: 27 records
October: 21 records
November: 22 records
December: 36 records

Depth and water temperature

Depth

Mostly recorded at 0–8 m · Deepest record: 63.5 m

0–10 m: 10 records
10–20 m: 0 records
20–30 m: 0 records
30–40 m: 0 records
40–50 m: 0 records
50–60 m: 0 records
60–70 m: 1 records

Water temperature

Recorded in surface water of 5–28 °C

4–6 °C: 2 records
6–8 °C: 1 records
8–10 °C: 8 records
10–12 °C: 9 records
12–14 °C: 7 records
14–16 °C: 2 records
16–18 °C: 4 records
18–20 °C: 0 records
20–22 °C: 0 records
22–24 °C: 0 records
24–26 °C: 0 records
26–28 °C: 0 records
28–30 °C: 1 records

Photos

(c) John Barkla, some rights reserved (CC BY), uploaded by John Barkla · CC BY · iNaturalist
(c) wild_wind, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Heidi Meudt, some rights reserved (CC BY) · CC BY · iNaturalist
(c) wild_wind, some rights reserved (CC BY) · CC BY · iNaturalist
no rights reserved · CC0 1.0 · iNaturalist
(c) Saryu Mae 前朝琉, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Saryu Mae 前朝琉, some rights reserved (CC BY) · CC BY · iNaturalist

Names and classification

English: Bluish Top Shell

Names in 1 more languages

Japanese: ミナミクロツケ

Other scientific names: Monodonta crusoeana, Monodonta nigerrima, Turbo nigerrimus, Zediloma digna

Similar species

Scorched monodont
Diloma aethiops
Speckled Periwinkle
Diloma concameratum
Mudflat Top Shell
Diloma subrostratum
Diloma aridum
Knobbed Top Snail
Diloma bicanaliculatum
Diloma coracinum

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).
301 open-data records from 1919 to 2014.
Species data updated November 2, 2026.

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