Random encounter.
Since ancient coin is mainly “real money” it’s going to be very rare for them to spawn.

Just keep jumping from island to island, don’t look for them and the will find you

@fafusta

They are quite rare matey! Yee will have to spend many hours journeying from island to island to find a random spawn. It's all luck me harty!

its just random with a pinch of luck
if you hear the sound of jingling coins,, then a ancient skeleton is spawn near you

https://www.youtube.com/watch?v=ZMsJO-UplX4&feature=youtu.be

i found meanwhile 5 of them, but they are really rare

good luck mate :-)

Ancient Skelly finds you. Not the other way around.

Just keep playing, usually they appear in any island, if you stay there for some minutes, but it is really rare, just play and forget about it, one day you will find one. Thieves Heaven is where i've found my last 2.