Homoplasy = something with same shape but different function?

And "ball of yarn" = ball of thread?

Context:
Homoplasy: A Good Thread to Pull to Understand the Evolutionary Ball of YarnScienceDaily (Feb. 24, 2011) — With the genetics of so many organisms that have different traits yet to study, and with the techniques for gathering full sets of genetic information from organisms rapidly evolving, the "forest" of evolution can be easily lost to the "trees" of each individual case and detail.