Halimocyathus is a genus of stalked jellyfish in the family Haliclystidae.

[1] The original specimen recorded by Clark in 1863 was found in the Massachusetts Bay attached to some Zostera marina seagrass.

[2] It distribution is unknown with a single other observation in the Bay of Fundy, Canada recorded by the Global Biodiversity Information Facility.

[3] Halimocyathus platypus has a deep funnel disk 6mm wide with a stork of 10mm high.

It has eight arms that are twice as long as they are broad each with 17–20 tick tentacles arranged in five rows.