Unidentified larva

Unidentified larva

Observation - Unidentified larva. Description: I'd cleared some vegetation from my small garden pond and left it by the pondside. After a few days I scraped up the frozen mass yesterday to expose this very unfrozen larva, about 2cm long. I thought it might be a butterfly caterpillar but it doesn't

I'd cleared some vegetation from my small garden pond and left it by the pondside. After a few days I scraped up the frozen mass yesterday to expose this very unfrozen larva, about 2cm long. I thought it might be a butterfly caterpillar but it doesn't look like anything on my FSC sheet...maybe a moth?