These are the fruits of the Singapore Rhododendron, Straits Rhododendron or Sendudok taken at the outdoor Butterfly Garden. It seems that some butterflies like to feed on it at the forest fringes.But there was another seed that was hanging on the left of the cluster of fruits. It looked like the seed of perhaps the nearby Calotropis gigantea (Crown Flower, Giant Milkweed).
The attached is a link on the common Singapore Rhododendron:
