Yeah, that`s what I assume. It seems we get the same effect. I have to try...

Btw. I played with the file I posted a bit more. The spikes I mentioned will disappear when you move the position of the rocks and also when you offset the function.

FYI the mat is scaled to 8. Now, in case you want to add an ecosystem, the scaling will jump back to 1. It`s sufficient to put it back to 8 and it will stay there afterwards.

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