Water Lily Ray creature design

Fantastical creature design.
I first got my inspiration whilst visiting a pond and thought how cool it would be if one of the lilypads were actually a creature. 
This then lead me to delve deeper into this idea.
This creature is fresh water and mimics a lilypad to be safe from predators and to disguise against prey. 
When moving downstream, it floats with its mouth open like a basking shark and is able to filter feed. 
Its other source of food would be from its camouflaged tendrils that look like kelp/weed. Creatures would swim through but then become immobilised by the venom (similar to jellyfish), then they would swim around and grab the prey.