Those are nanners, which are basically the inside of the anthers of a male cannabis plant. Normally, a male plant grows a pollen sac that collects all the pollen and ultimately releases it when the pollen sac is fully matured. Once the pollen sacs open, you'll see a banana-shaped structure inside. However, here only this structure is growing without forming a pollen sac. This is usually triggered by stress. If there aren't too many of these little bananas, you can try to remove them thoroughly. It's best to moisten them first to minimize the risk of possible pollen release. However, if there are a lot of nanners or if nanners continue to form in the future or more frequently, I would consider removing the plant or at least separating it from the others.