I thought it was a large group of individual Larvacean houses clumped together. I tagged as many as I could. Any other thoughts?
Oh, I'm sorry you got such a difficult image to classify. This is actually a cluster of some #protist we don't classify for this project. Here is a clearer image of another cluster of the same type of protists: APK00003b5 - they're beautiful, aren't they?
Here are some facts about Larvaceans and details about all three type of their houses: https://talk.planktonportal.org/#/boards/BPK0000005/discussions/DPK0000bj5
And/Or here for more image examples of Larvacean houses if needed: https://talk.planktonportal.org/#/collections/CPKS000090
Hope that will help you to recognize them better 😃 Feel free to ask any question when having troubles.