We've been making our own kombucha for years and the scoby that produces it grows gradually. The summer weather has meant it's grown a bit faster so is ready to split again if anyone wants any to try to make their own. It's a weird looking thing hence I haven't added a photo in case people don't want to see it unexpectedly while browsing freegle!
Search online for how to do it but basically add sugar and tea (we use green, black, white or rooibos) and sugar and it does it's thing if gently covered in a bowl or put in a fermentation jar.

Scoby to make kombucha (Whitemans Green RH17)