Hazwan also claimed that the photo had been obtained on 11 December, and had been posted by him/her that same day on this Project Noah page. In addition, Hazwan stated that the coordinates of the location where the creature had been photographed were Lat: 4.97 Long: 114.90. This is near the coast within Brunei's capital,Bandar Seri Begawan.
Brunei mystery beast, Hazwan
The armoured anomaly present inside what looked like a white bucket or similar vessel containing some yellowish water was certainly very unfamiliar in appearance, and the lack of anything in the photograph that could provide a scale to gauge its size only served to heighten the mystery surrounding it. On first sight, it looked like some bizarre form of crustacean, but it seems to lack the sizeable number of limbs and dual pair of antennae typically associated with these arthropods. Also, the pincer-like cerci seemingly present at the posterior end of its body were much more reminiscent of the abdominal forceps of earwigs and certain other insects than of anything exhibited by a crustacean. Yet I am not familiar with any form of aquatic insect – adult or larval stage - that is even vaguely similar in appearance to the Beast of Brunei. Could it therefore have been some form of terrestrial insect that had inadvertently fallen into the river and had then been spied and caught by whoever had photographed it? As it so happens, there is a group of terrestrial beetles that do offer at least a superficial resemblance to this mystery animal. Coleopterans belonging to the taxonomic family Lycidae, they are known, for good reason, as trilobite beetles. For whereas the adult males are typical-looking beetles (and also fairly small, only around 1 cm long), the much larger adult females (up to 6 cm long) and also the juveniles sport an ornate protective armour of segmented, spine-bearing plates known as scutes that do recall the appearance of those long-vanished prehistoric arthropods the trilobites – and also the Beast of Brunei, as seen in the comparison photograph above.
Brunei mystery beast and trilobite beetle

Beast of Brunei on left (© Hazwan), and a female Duliticola hoiseni trilobite beetle from Malaysia on right

 Yet despite spending a considerable time perusing images online of various species of trilobite beetle (insects, incidentally, that do include Borneo within their distribution range), I have failed to find any that provide a convincing correspondence to the Beast of Brunei. Possibly the closest are those of the genus Duliticola(which is actually named after Borneo's Mount Dulit), but the Beast's body is proportionately too long and slender, and its cerci are unprecedented among trilobite beetles.
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