[cma]

Eyes are a good example of conservation and path dependence, development is initiated by a fairly highly conserved gene:

https://en.wikipedia.org/wiki/PAX6#Species_distribution

[Retric]

Being reasonably conserved has minimal predictive power. Yes, knocking it or a closely related gene out out harms eye formation in a wide range of species but it says little about what specific structure ends up being formed.