Is this some kind of spider egg mass?   It is pretty large - the size of a chicken egg.  Found attached to a hand rail in the country park.  

frog egg

shouldn't frog eggs be in water or at least some place moist as tadpoles live in water......

A Field Guide to the Amphibians of Hong Kong states that the egss of the Brown Tree Frog Polypedates megacephalus are "laid in a pale yellow frothy mass suspended
from tree trunks/bushes or glued onto the sides of walls, big rocks above pools of water". Presumably when the tadpoles emerge they fall directly into the water below.

It is fairly common to see this frothy mass on the sides of catchment channels and on dams, such as the dam next to the road at Tai Po Kau.

David