Fossils of Spriggina are known from the Ediacaran period, around . The segmented organism reached about 3 cm in length and may have been predatory. Its bottom is covered with two rows of tough interlocking plates, while one row covered its top; its front few segments fused to form a head, which may have borne eyes and antennae. Spriggina's affinity is currently unknown; whilst once considered an annelid worm, or even a rangeomorph-like frond, it is now considered to be an arthropod, perhaps related to the trilobites.