What is this?

[Jarl]

I am curious if anyone knows what this rock is. It was suggested that it might be a type of sponge coral but I don't think that is what it is. I could be wrong. One reason I don't think that it is is because it's porosity is too random and without the characteristic details of the majority of past and present sea life, as in corals. But that is only one simple reason, again, I could be wrong as I am no expert. It seems to me that it's production was the result of being liquid and highly gaseous at the same time. That leads me to think that it may be a type of volcanic spindle bomb. Most of the shapes I find these in are roundish and show some habit of elongation/tear drop shape. My thought is that this is possible if it is liquid and flying into the atmosphere, perhaps as an extruded blob of magma...or something. Your thoughts would be appreciated. Thanks!

 

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[Eu_citzen]

A limonite concretion, maybe?

 

[Jarl]

Eu_citizen, I am not sure, it is possible. Thanks for the suggestion. By the way, where in Sweden are you from?

 

[Eu_citzen]

Jarl, from the south eastern parts of Sweden.
I'm located in the middle of a interesting geological feature called Trans scandinavian igneous belt.

 

[rock]

If it is heavy I would say weathered iron ore. That is what I find sometimes where I live at and it looks just like it. But I could be wrong.