FusionDex

Dhelsect will spend much of its time lying motionless on the ocean floor, mimicking a simple pile of seaweed. If something swims close, it springs to life and sends out kelp-like tendrils that drag its new prey down to be consumed.

Dhelsect are known to infest the roots of large trees en masse and drain nutrients. The soul of seaweed adrift in the waves became reborn as this Pokémon.