Hey there I have a 35 dsa lagoon tank and in the recent weeks I’ve had these random things pop up not sure what they are. I asked other forums and no one knew any help would be appreciated thank you !
Videos can be pretty tricky to upload here - most people upload them to YouTube and link them here from there.
That said, those are colonial hydroids (the first video shows them pretty clearly once it zooms in) - I'm not sure which species (there are quite a few branching species like those), but (with a cursory glance) it reminded me Obelia spp.