I am having issues with the light blue Jellyfish. I read through here and planted a "heap of stones" then grew a "rose seabed" next to it, but nothing. I tried moving them around a little and still nothing. Does it matter where you put it, ie: do they have to be on a ledge or away from other plants or anything? Doesn't seem to be working I'm on level 21, and yes that enigmatic seed challenge is a pain!
My username for reef is same as here