Bonds between monkeys may be Asymmetric (A) or Symmetric (S)

If the two sites are joined by a symmetric link (S) then a pair with twofold rotational symmetry is produced and this cannot grow further without introducing a new link, which in turn maybe either symmetric or asymmetric. (These comments are best understood by manipulating a few monkeys.)

Green, NM (2006) Monkeys Ape Molecules: An online exhibition