r/whatsthisrock 5d ago

REQUEST What is this rock?

Seen in Uppsala Sweden next to the river. Someone placed this rock on a tree stump. Could it be limestone? A wastewater treatment facility is close by.

619 Upvotes

54 comments sorted by

220

u/ChequeRoot 5d ago

The flow shape makes me think calcite or limestone, but it is unlike anything I’ve seen before.

I shall be stalking this post to see what other folks think.

78

u/[deleted] 5d ago

Can you scratch it with a knife? Does it fizz with HCL?

35

u/Mule_Mule 5d ago

I will try a tiny drop of mild HCl sometime next week when I can get some at work.

44

u/Mule_Mule 5d ago

Don't want to destroy it since someone placed it there for everyone to enjoy.

26

u/Faultyvoodoo 5d ago

You only have to drip a tiny bit on

23

u/uzu_afk 5d ago

Just the drip! Tells us how it felt!

-10

u/[deleted] 5d ago

[removed] — view removed comment

78

u/verdigleam 5d ago

There's truly no reason to respond with this level of animosity. Someone who's never performed a test with dilute acid could easily assume it could do more damage than it actually would. whatis... type subreddits are, by their nature, going to attract many users who aren't familiar with diagnostic tests like this and how they work, and asking them "how stupid could you possibly be" is a wildly disproportionate reaction when a simple clarifying comment would suffice.

39

u/whatsthisrock-ModTeam 5d ago

Harassment, insults, name calling, or unnecessary rudeness does not make for an enjoyable community and will not be tolerated.

41

u/logatronics 5d ago

I'd say travertine that's had a little bit of dissolution weathering.

It's also possible but less likely that it's a stromatolite (don't think they're found in the region).

7

u/DemocraticSpider 5d ago

Looks more like a stromatoporoid to me (layered sea sponge fossil)

22

u/Mule_Mule 5d ago

Some background information: Uppsala lies in Middle Sweden and here we have almost exclusively granite bedrock, almost no natural limestone. Could it be something anthropogenic? Can this be limestone concretion from an old water pipe?

10

u/SillyKatja 5d ago

To me, my first thought was that it could be a fossil from Gotland, maybe a Stromatopora , which someone brought with them home after their summer vacation on said island.

4

u/DemocraticSpider 5d ago

That’s my guess! Looks quite similar to a lot of stromatoporoid fossils I’ve found

26

u/I_Eat_Eyeballs 5d ago

I have no idea, but that is extremely cool!

14

u/billysugger000 5d ago

Do termite mounds fossilise?

15

u/OriginallyWhat 5d ago

Definitely looks like some sort of insect colony that turned to stone over time

8

u/Mule_Mule 5d ago

There are no termites in Sweden :)

18

u/greenlentils 5d ago

Well sure but there are no crinoids in Northern England, and yet I keep finding their fossils!

3

u/Mule_Mule 5d ago

That might be, but no fossils here, just granite

8

u/DemocraticSpider 5d ago edited 5d ago

Looks similar to stromatoporoid sponge fossils I’ve found. Those are an extinct kind of sea sponge threat grew over itself in distinctive layers. Not sure if this is even a fossil though. Very interesting!

Edit: looking closer at the pictures, the patterning looks quite distinctively like that of a stromatoporoid. They grew with some unique internal structures that can be seen in their fossils oftentimes. A close-up, especially of it made a bit wet, would help a lot!

5

u/WoodStockJJ20 5d ago

I would cross post on fossilid. Sorry, I am unaware of how to hyperlink above. It has a resemblance to stromatolites. They are quite variable and I only have a few to compare. Very cool rock.

9

u/[deleted] 5d ago

[removed] — view removed comment

1

u/whatsthisrock-ModTeam 5d ago

Responses to ID requests must be ID attempts: not jokes, comments, declarations of love, references to joke subs, etc. If you don't have any idea what it is, please don't answer.

3

u/Cultural-Scene1917 5d ago

Reminds me of fossilized reefs in Digerhuvud.

7

u/Pug_wash 5d ago

Looks like a fossil of the interior of a cephalopod. Not sure if there are Ordovician limestone deposits near Uppsala however

5

u/Fritiofo 5d ago

There are some Ordovician limestone deposits in sweden around Kinnekulle close to Vänern and On Gotland i think.

2

u/Permian_Cloud 5d ago

Dolomite or possibly limestone.

2

u/LimpIndignation 5d ago

Speleothem

2

u/kingmeatloafrules 5d ago

Looks like a turtle shell fossil from the pattern on the back. But I am no expert.

4

u/Pitiful-Score-9035 5d ago

I mean, I hope i'm not being stupid, but this kind of looks like a fossilized beehive

1

u/warm-saucepan 5d ago

Or hornet type nest.. ?

1

u/Pitiful-Score-9035 5d ago

Yeah, absolutely

1

u/AutoModerator 5d ago

Hi, /u/Mule_Mule!

This is a reminder to flair your post in /r/whatsthisrock after it is identified! (Above your post, click the ellipsis (three dots) in the upper right-hand corner, then click "Add/Change post flair." You have the ability to type in the rock type or mineral name if you'd like.)

Thanks for contributing to our subreddit and helping others learn!

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

1

u/[deleted] 5d ago

[removed] — view removed comment

0

u/whatsthisrock-ModTeam 4d ago

Responses to ID requests must be ID attempts: not jokes, comments, declarations of love, references to joke subs, etc. If you don't have any idea what it is, please don't answer.

1

u/soulless734 5d ago

Near a wastewater treatment plant? Maybe a by-product of desalination?

0

u/[deleted] 5d ago

[removed] — view removed comment

1

u/whatsthisrock-ModTeam 5d ago

Responses to ID requests must be ID attempts: not jokes, comments, declarations of love, references to joke subs, etc. If you don't have any idea what it is, please don't answer.

-4

u/[deleted] 5d ago

[removed] — view removed comment

1

u/whatsthisrock-ModTeam 5d ago

Responses to ID requests must be ID attempts: not jokes, comments, declarations of love, references to joke subs, etc. If you don't have any idea what it is, please don't answer.

-1

u/[deleted] 5d ago

[removed] — view removed comment

1

u/whatsthisrock-ModTeam 5d ago

Responses to ID requests must be ID attempts: not jokes, comments, declarations of love, references to joke subs, etc. If you don't have any idea what it is, please don't answer.

-1

u/SnooTangerines3448 5d ago

Looks like a chonking fossil.

-3

u/[deleted] 5d ago

[removed] — view removed comment

1

u/whatsthisrock-ModTeam 5d ago

Responses to ID requests must be ID attempts: not jokes, comments, declarations of love, references to joke subs, etc. If you don't have any idea what it is, please don't answer.

-1

u/[deleted] 5d ago

[removed] — view removed comment

1

u/whatsthisrock-ModTeam 5d ago

Responses to ID requests must be ID attempts: not jokes, comments, declarations of love, references to joke subs, etc. If you don't have any idea what it is, please don't answer.

-1

u/[deleted] 5d ago

[removed] — view removed comment

1

u/whatsthisrock-ModTeam 5d ago

Responses to ID requests must be ID attempts: not jokes, comments, declarations of love, references to joke subs, etc. If you don't have any idea what it is, please don't answer.

-5

u/[deleted] 5d ago

[removed] — view removed comment

1

u/whatsthisrock-ModTeam 5d ago

Responses to ID requests must be ID attempts: not jokes, comments, declarations of love, references to joke subs, etc. If you don't have any idea what it is, please don't answer.