I chose "Turk's turban" because it is an already observed species in Sri Lanka, but, could it be "The Musical Note"(Rotheca microphylla)? I didn't see any observations in Sri Lanka but the plant does have a rather wide range, so is it unlikely for it to be here as well?
Baker's Falls, Horton Plains NP, Nuwara Eliya, Sri Lanka.
Other observations of Oberonia wightiana in the same location, looks similar. Horton Plains NP, Nuwara Eliya, Sri Lanka.