Flat-backed millipede, Milpe Bird Sanctuary, Ecuador

Possibly genus Barydesmus. These are harmless leaf composers yet you should not handle them with your bare hands, as they store chemicals in their glands. Interestingly, some creatures in the cloud forest have learned to make use of this. For example, some monkeys rub millipedes on their skin to protect against mosquitos.

Source of this info:
https://www.mashpilodge.com/blog/millipede-more-or-less-one-thousand-feet/