Keris hilts with raised curved backbones

[Loedjoe]

Two keris hilts, Sumatra, probably both Palembang.

The first, mainly of natural formation?, possibly an abstract Garuda, with raised and curved backbone, hunched shoulders, large featureless head poking forward, with a blunt nose, Palembang-style carved decoration on the base at the front, marine? ivory. 7.2 cm.

The second of wood, mainly of natural formation, the head with lumps all over it, with raised and curved backbone. A rather sinister and forbidding figure. Hilt and selut (which is fixed firmly to the hilt), 8.5 cm.

Does the curved raised backbone indicate something?

I would love to see similar hilts from others on the Forum, and of course to learn more about this 'type'.