Spiky ball
A useful common-language name for the round branch of the modern urchin category: compact center body, flexible arms extending in every direction, and often a profile intended to hover, fall slowly or pulse while suspended.
Urchin bait
The broader generic term currently used across fishing media for this family of many-armed soft plastics. In everyday use, “urchin” often refers to the same round profile as “spiky ball,” but some writers use urchin more broadly.
Fuzzy dice / dice bait
Usually the cube or block-bodied branch. Bassmaster's 2026 coverage explicitly separated soft-plastic dice baits with skirt material from the round “urchin” or “spiky ball.” That is the cleanest working distinction we have found.
Coike
Coike is a HIDEUP product-family name associated with the Japanese baits that helped establish the category. It is widely referenced in current coverage, but it is not the generic word for every spiky ball or urchin bait.
The simple rule
If the bait has a round center body, calling it a spiky ball or round urchin is useful. If the center is a cube/block, fuzzy dice or dice bait is more descriptive. If somebody calls either one an urchin-style bait, check the actual shape before assuming what they mean.
For the broad category — including size measurement, material, micro applications and multiple species — see GenericUrchinBaits.com.
Sources
Bassmaster — ball of fuzz / dice bait
Bassmaster — spiky ball specifics
Major League Fishing — urchin craze