yes we saw your photos and read your post.. which also asked what it is...do you saw the photos ? Or I have to keep going to EXPLAIN to EVERYONE ISN'T SLUG !!!
Check there is a DISK, there is a MOUTH on that DISK, It stick to the glass like ANEMONE, it have CIRCULAR STALK.
Honestly, because of people who don't read I update the post few times (one-2 to make mistake ok, can accept it) but after I SAY ISN'T NUDI, so isn't. C'mon Please, if you don't know what is it, don't just say that after is discussed already. PLEASE ! I start to sound rude, SORRY !
i suppose it could be a branching anenome (if you are so confident).. they do exist. I have just never seen an anenome react so violently to light.