Immortal green Hydra with child

Body about 4mm long, tentacles about 2.5mm long when extended.
Found firmly anchored to a bundle of decaying plant matter in a stagnant pool.
This one with a clone budding from its side.
Now if only we can figure out how they (allegedly)overcome senescence.
While watching it, a cladoceran got caught in its tentacles. It appeared to be resistant to the hydroid's stings and was released after about a minute.