Coral is found in the underwater levels of Crash Bandicoot 3: Warped.  It is usually found in the submergible sections of these levels. Coral can only be destroyed from a bullet from Crash's submergible.

Crates are often found surrounded by coral. When this is the case, Crash must shoot the coral to break the crate. Therefore, in order to get the box gem, he must avoid hazards while on the submergible, as hitting any hazard will make the submergible go away, even if Crash also has an Aku Aku mask.