In that case it would be Keter, because if the fundation can only secuerly contain part of it, it's obviously not safe, Euclid it's when something can be completely contained but it's too unpredictable or erratic.

Okay thanks

Tl;dr Whitecrow233 is correct.

I'm sorry for not answering the question at first. I admit that I just wanted to show you the actual SCP Fandom Wiki.

As for your question, here are some examples of SCPs that are only partially contained and their classes:

• https://scp-wiki.wikidot.com/scp-1534 (Keter)

• https://scp-wiki.wikidot.com/scp-1678 (Euclid)

I got these using the SCP Wiki search tool: https://scp-wiki.wikidot.com/search:crom

Its probably a mixture of the above two responses. Difficulty in containment is a factor, but if you can contain one element while the other roams free, and its more or less fine, then Euclid would be sufficient. If theres always one part wandering around and it causes problems, then it'd be Keter.

Actually, I'm pretty sure it would be Apollyon, since, "Apollyon-class SCPs are anomalies that cannot be contained, are expected to breach containment imminently, or some other similar scenario." Since it clearly can't be fully contained, it seems like it fits this mark perfectly, as it can't be properly contained and could technically break out at any moment.