- Natural vs Synthetic Fibers.. Please help me out

So I have a sample piece here. I've conducted some tests and I have to figure out if it is synthetic or natural. Here is what I found about my sample:

- It has a knot strength of 14N
- It has a tearing strength of over 20N
- When put near flame, it starts burning (not slow but not too quickly) - the ash is black and it doesn't shrink or melt like nylon or polyester would.. It took 4 seconds to extinguish it by hitting it - half of the sample was left untouched and there's a small amount of soot

Now here's the problem, from the burn test it's most likely a natural fiber, since synthetics would melt and shrink, or have different burn results.
I did the water absorption test:

- At first, it adsorbed the water. There was a large water bubble at the top, and it simply rolled off the thing. However, when I put water on it again - it ABSORBED it. I did notice some "seeds" being removed when i tried to dry it up...

Could anyone give me a hint on what it could be? what further tests should I do?
So far, it acts as if it is a mixture of both - but we have to identify it as one or the other. Any ideas?