I remembered this critter flew past me and landed on a tree trunk in front of me during one of my outings many weeks ago. Out of curiosity, I took a closer look and noticed it was a moth, very well-camouflaged and blended almost perfectly with the tree bark. Since then, whenever I bumped into an old tree trunk with dull and unattractive bark, I would spend a few more seconds examining the tree trunk. I have begun to discover that there are interesting creatures living on tree trunks.
I guess this is a kind of Darkling beetle (Strongylium gratum ?) which was found on a tree trunk covered with lichen on the summit of the Bukit Timah hill.
So next time when you come across an old big tree covered with blackish and dull bark, slow down and take a look because you may discover something you have not seen before.