"'The neutron and proton I believe you have already met. In the next row you have the sigma particle, which can manifest with both positive and negative electric charge and also with no charge at all. It consequently appears as if it were three different particles. In the center of the pattern you have the lambda, which is a single particle with no charge. These are all strange particles,' he added.
'They all seem very strange to me, ' agreed Alice, as she came over to look at them more closely.
'No, no. Strangeness is simply a property possessed by certain particles and which happens to have been given the name of strangeness. Rather like electric charge, you know—except that it is totally different,' he added unhelpfully. 'The remaining two particles are both the Cascade. It comes in tow different charge states, so there are two of it,' he explained. 'it is double strange, of course.'
'Of course,' echoed poor Alice."
-Alice In Quantumland, p148-149
by Robert Gilmore