Neesia synandra is a close  relative of the durian in the Malvaceae family.

Like many seeds in the Myristicacea (nutmeg ) and Meliaceae (langsat  family)  Neesia  seeds are targeted specifically at hornbill dispersal.

When the seeds are ripe the 5 wings of the large Neesia fruit splits open exposing the seeds surrounded by a tasty aril. However only hornbills have bills  thin enough and long enough  to  access the  gap in the splits to obtain the seeds.

The seeds are surrounded by sharp hairs which prevent  most primates from accessing them without tools.

Only the orangutan is intelligent enough to use a stick to access and predate the tasty Neesia seeds.

Van-schaik-Knott-2001-geographic-variation-in-tool-use for eating Neesia

Neesia photos by Arlene Walshe taken at Temburong, Brunei Darussalam.

Orangutan illustration by Karen Phillipps