Crystal like stone

Sorry about quality of pics, they are vid stills. On the top of this larger karst rock if you look closely you can see a perfectly hexagonal rock that looks like an old wooden 2x2. It isn’t, it’s hard like rock, and based on where I saw this, a beach that can only be accessed at a very low tide, in Malaysian Borneo, and how it sticks out of this very hard larger rock, I don’t think it can be fossilized wood, I can’t imagine how it got there and there was nothing like it anywhere around that area.

Can rock grow like crystal? I climbed on the rock and struck it with my hand and a metal flashlight and it wasn’t going anywhere, it looks a lot like some of the crystal formations I’ve seen in another post. If it was a crystal of some kind, it didn’t have any crystal-like surface, it was a thorough opaque gray and because it’s underwater at high tide, if it was simply aged and colored, I expect I would have seen some evidence of that, but it didn’t seem to be, it looked like a gray stone.

Sorry if this is a dumb question, I understand that crystals are rocks, but i haven’t seen non-crystal like rocks like this before, so i figured i’d ask.

Hi, that looks like basalt from a lava flow. It probably formed that way due to cooling by water. As for how the 2x2 “stone” got there. It probably was there before the basalt was.

The larger stones are karst, according to the experts; the region is full of massive karst rock forms. It’s that 2x2 thing that I don’t understand. I have a theory but it’s a guess.