Did you spot these clouds in the sky Saturday afternoon? If so, you are looking at virga, which is the name for precipitation (like rain) that falls from a cloud but evaporates before reaching the ground.
Sometimes, the combination of the altocumulus cloud and the rain shaft resemble a jellyfish, which is why they are sometimes referred to as "jellyfish clouds", though that is not an official cloud classification.
But why does the rain evaporate before reaching the ground? The reason is due to different amounts of moisture within the atmosphere. A mile or so above the ground, enough moisture is available for water vapor to condense into liquid water droplets -- and a cloud forms. Eventually, the liquid water droplets fall from the cloud into a layer of air that is much drier compared to the cloud layer. The liquid water falls and evaporates back into water vapor, with a result that resembles "tendrils" in the sky.
Did you snap a picture of virga, or "jellyfish" clouds on Saturday? If so, submit your photo!