Parenchymella larvae of Spongillidae (Porifera)

iNaturalist observation: https://www.inaturalist.org/observati... At the time of sampling there were many parenchymella larvae floating in the water. And two species of sponges were present. Green finger-like sponges - which I identified as Spongilla lacustris https://www.inaturalist.org/observati... (with endosymbiotic algae) and colourless https://www.inaturalist.org/observati... (yellowish-white) sponges growing in shapeless colonies on Fontinalis antipyretica https://www.inaturalist.org/observati... (water moss). The larvae themselves are without endosymbionts, and I have seen a few larvae attached to the surface of a white sponge. So I think the larvae belong to the colourless sponges. But I can't be sure because I don't know much about these organisms and I haven't been able to find enough information. Sampling location: A water sample was collected from Istok Lake near the shore, where snags and aquatic vegetation were present. Date and time of collection: 16 Jul 2023 at 3 PM Date and time of observation: 17 Jul 2023 at 8 PM The sample was stored at room temperature in a plastic container. Phylum: Porifera. Class: Demospongiae. Order: Spongillida. Family: Spongillidae. I have 30 minutes of unedited footage stored. Should you be interested in viewing it, kindly inform me and I will endeavour to share the footage with you. Music: The Tides - Dream Escape