I have prepared a mangosteen extract by grinding the dried pericarp into powder and macerated it for 3 days with ethanol 96%. The mixture was then filtered and the solvent was evaporated in a rotary vacuum evaporator until it gains a thick consistency. After that, I decided to store the extract in the fridge at a temperature of approximately 5 degrees celsius. Fast forward two weeks later, I found these at the bottom of the flask. Then, I took some samples of the precipitate and put them under the microscope.

Anybody might have a clue what these are?