Mysterious Things

Question
Hi There
I'm writing on behalf of my mum who has the freshwater aquarium, as she dose not have internet access only through me.
She has a Clear-Seal corner tank, and about 10 weeks she brought a new tank after it matured she transfered her fish from the Clear-Seal to her new tank the Juwel 190 which is running perfect...... But in her clear-seal she kept behind her female Guppies and her babies, over time about a week or two after she transfered the fish these tiny things appeared. I have myself search for then myself but had no luck and i came across your site. My mum was told that 'these things' aren't parasites or a water flea from her local fish stores, she went to two and one of them have requested from her more of 'these things' but still not came up with anything, and the other has suggested that it is down to her over-feeding but my mum is having that answer. The babies aren't bothered with then and they aren't bothered by the babies. The temperature of the tank is around 80c, there's one plant and a small porous rock and has gravel on the bottom.
'These things' look like trough a magnifying glass a small shell like body, like a muscle but round and cream in colour with brown lines like veins.
They move very fast along the bottom and over the rock, feeler like legs come out at the front of the shell to move. They seem to live in the gravel and the rock. May you help me find out what they are because now I'm fascinated by them along side my mum.
                        Kind Regards
                        Natasha Grant

Answer
Hi Natasha,
Wow, interesting!

There are many kinds of scavengers in your aquarium that can get in in one way or another. They may be Copepods but I'm not 100% sure. All are peaceful scavengers that are harmless in your tank. But they are indicative that there is an overabundance of nutrients in the water and you should step up the water change schedule.

Doing small daily water changes around 20-30% would help in removing their numbers, and the food source that is keeping the population going.

I hope this helps and best of luck!
Karen~