This is more higher than deeper, though, since the matter we know already consists of three quarks (baryons) or one quark and one anti quark (mesons). A pentaquark is basically 4 quarks and one antiquark, a combination of a baryon and a meson in one.

Thanks, that quote is making it a little clearer. I'll try to simplify even more:

When a particle consists of quarks (not all particles do; e.g. an electron is not made of quarks), "the numbers" need to "add up".

"The numbers" are the so-called "color charge". No relation to real colors, it's just a name :). The color of a quark can be red, green or blue. In total, baryons (big fat particles, e.g. protons and neutrons) have to be white.

Example: Proton: Blue up-quark, Red up-quark, Green down-quark. R+G+B = white.

As you can see, there can't be a baryon with 4 quarks -- it would be RRGB or RGGB or RGBB or RRRG...; definitely not the same amount of red, green and blue.

But 5 quarks are possible again, because there are anti-quarks, which also have an anti-color; you have 3 quarks that are R+G+B, and then e.g. another Red one, and an Anti-Red. The Anti-Red cancels out 1 Red, so color-wise you again have RGB=white.

And now the LHC has shown that those theoretical 5-quark-particles ("pentaquarks") actually exist. That's quite impressive.

You could have particles made from gluons, called glueballs...