Raspberry peanut butter mead, this happened after racking into tertiary. Primary and secondary had raspberries freefloating in the container, so it miiiight just be floating bits of raspberry. When I shake it up, they briefly sink and float back up.
That looks to me like the shells of the drupelets of the raspberries that have been squashed, so all of the colored juice has come out. Presumably racking it over also liberated some co2 which caused it to float. I would refrain from opening the fermenter cause every time you do, you let in O2 and roll the dice on infection.
