It is not a seed pod but a baby plantlet. New plantlets grow at the tips of the flower stems, weighing them down until they bend to touch the ground and take root. The new plants will eventually repeat the process, causing the iris to "walk" across the garden, hence the common name of 'walking iris'.

Thanks for quick answer! But this is attached to the plantlet...not the plantlet itself. Plus never before have I seen this on a plantlet