Amphidetus Agassiz, 1836 Echinocardium is a genus of sea urchins of the family Loveniidae, known as heart urchins.

The name is derived from the Greek ἐχῖνος (echinos, "hedgehog, urchin") and καρδία (kardia, "heart").

[2] The genus was first described in 1825 by John Edward Gray,[3][4] and the type species is Spatangus pusillus Leske, 1778 by subsequent designation.

[3][5] In 1836, the genus Amphidetus was described by Louis Agassiz,[3][6] and is now considered a synonym of Echinocardium.

This article about a sea urchin is a stub.