Hi
We have a large pond fed by a natural spring (UK). I'm really enjoying watching all the pond life and researching it online later. I'm struggling to identify this creature however.
I've included photographs but I'm afraid they are poor quality especially as they were taken above the water (the creatures look like sets of rusty pliers in them!). I managed to catch two of them together in one photo. I'm unsure of its a split pupae or its actual body. I considered it being a caddisfly but from my (attempts) at researching I understand they 'collect' their cases, but I've seen 3 creatures with identical shells so it seems unlikely? the only additional information I can offer is that they crawled/stumbled over the bottom of the pond and there appears to be a translucent 'tail' that's very slender.
Thanks

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Hard to tell from the photos but my first thought ws also caddis fly larvae of some type. Can you catch one and have a closer look at the "shell" to see if it really is part of the animal? individuals of particular species of caddis use the the same materials and "design" so if they are all using the same supply of small twigs or similar that could be what you are looking it.