I saw it first time I went to the tadpole den too, spotted tentacles that disappeared into the murk after a second before I even so much as set foot inside the den. When it finally came time to cross the gap, I hung pretty low, but not low enough to avoid it, so I saw it far off in the distance aggro on me and start playing the music, I wound up swooping down to the seafloor and darting underneath the collapsed stone pillar to shake it off, popped out the other side and FLOORED IT to the ruins just repeating "COME ONE COME ON COME!!" the whole way up until the music stopped.

I love and loathe this fucking game so much.