Animal Care/Snail shells with D shaped openings

Hermit crabs that usually prefer shells with "D" shaped openings: Equadorian/Pacific hermit crabs or "Es" (coenobita compressus) Cavipe hermit crabs or "Cavs" (coenobita ) As pets they tend to give preference to particular snail (class Gastropoda, phylum Mollusca) shells (Picture2  links may contain pictures of shells that have been misidentified; not all shells at the "common names" links may be appropriate for hermit crabs): Superorder Caenogastropoda - Order Sorbeoconcha babylon shells (common names; family Babyloniidae - Family pictures) - Examples: Spotted Babylon (Babylonia areolata) - Regions: SE Asia, Philippines, Formosa, China - Picture - Picture2 Formosan Ivory Babylon (Babylonia formosae) - Regions: Formosa, Taiwan - Picture - Picture2 Japanese Babylon (Babylonia japonica) - Regions: Korea, Japan, Taiwan - Picture - Picture2 Lutose Babylon (Babylonia lutosa) - Regions: Japan, Sri Lanka - Picture - Picture2 Spiral Babylon (Babylonia spirata) - Regions: Pakistan, Sri Lanka, Taiwan - Picture - Picture2 moon shells (common names; family Naticidae - Family pictures) - Examples: Spider Moon (Natica arachnoidea) - Regions: Mozambique-Andamans; W.Pacific; Australia - ZipCodeZoo entry - Picture - Picture2 Calf/(Red) Banded/Yolk Moon Snail (Natica vitellus) - Regions: W.Pacific; Indian Ocean - ZipCodeZoo entry - Picture - Picture2 Fly-specked Moon Snail (Naticarius stercusmuscarum) - Regions: Mediterranean; NW Africa - ZipCodeZoo entry - Picture - Picture2 Shark's Eye or Atlantic/Double Moon (Neverita duplicata) - Regions: Massachusetts,USA-Yucatán, Mexico; Bahamas - ZipCodeZoo entry - Picture - Picture2 Lewis'/Western Moon (Polinices lewisii) - Regions: Vancouver Island,Canada-N.Baja California, Mexico - ZipCodeZoo entry - Picture - Picture2 White Moon Snail (Polinices porcellanus) - Regions: Cape Verdes; St Helena; Florida,USA-C.Brazil; Mid-Atlantic Ridge - ZipCodeZoo entry - Picture - Picture2 Lined Moon Snail (Tanea lineata) - Regions: N.Indian Ocean-Japan & W.Australia - ZipCodeZoo entry -Picture - Picture2 Tiger Moon (Tectonatica tigrina) - Regions: E.Africa-SE Asia & SE Australia - Picture - Picture2 David Harp shells (Harpa davidis ; family Harpidae - Family picture) - Region: Andaman Sea - ZipCodeZoo entry - Picture - Picture2 Superorder under revision - Order Cycloneritimorpha nerite shells (common names; family Neritopsidae - Family pictures) - Examples: Black Nerite (Nerita atramentosa) - Regions: S.Queensland-W.Australia; New Zealand - Picture - Picture2 Lined Nerite (Nerita balteata) - Region: Vietnam-N.Australia - Picture - Picture2 Polished/Polite Nerite (Nerita polita) - Regions: Indo-W.Pacific; Red Sea - ZipCodeZoo entry - Picture - Picture2 Ornate/Rough-ribbed Nerite (Nerita scabricosta) - Regions: Baja California, Mexico-Peru; Galápagos - ZipCodeZoo entry - Picture - Picture2 Red Nerite (Neritina communis) - Regions: W.Pacific; Philippines - ZipCodeZoo entry - Picture - Picture2 Olive Nerite (Neritina usnea) - Regions: Florida,USA-Colombia; Greater Antilles; Trinidad; Mid-Atlantic Ridge - ZipCodeZoo entry - Picture - Picture2 Violet Nerite (Neritina violacea) - Regions: Philippines-India & Australia - ZipCodeZoo entry - Picture - Picture2 Zebra Nerite (Neritina zebra) - Region: Honduras-E.Brazil - ZipCodeZoo entry - Picture - Picture2