As with all types of particles, given enough time, WIMPs will decay. This means, that if we want to look for WIMPs in todays Universe, we need to find the most stable WIMP because that will be the only type of WIMP that has not decayed into ordinary particles. The lightest of the WIMPs is theorized to be the most stable particle and will therefore be found throughout the present Univere. The most stable WIMP is called the neutralino. (4, 5)