What would you call a "sheath" for a spherical object?

I was looking for a word to describe a sort of cloth sheath you could use to store a boule de pétanque. I found myself in the strange position of knowing the appropriate word in French (housse) and in Spanish (funda) but not in my native language. Both these words basically mean a covering. Those are the words used in their respective languages for a (hard or soft) guitar case for example.

I was imagining a kind of form-fitting sock that the boule could be put in. The image I have in mind is something like the socks sold as protective covers for mobile phones:

What would that be called in English? I tried dictionary translation but got things like sheath, slipcover and dust cover. Sheath does not work on a sphere and the other two don't work for me in this context either (please let me know if you disagree).

The best I could come up with is a jacket but again, not as general as case. Basically I am looking for a word that would describe a form fitting, soft protective cover without implying hardness (case), a particular shape (sheath) or a specific use (dust cover makes me think of machinery and slipcover of furniture).

EDIT: I just thought of sleeve as in record sleeve but I am not sure that I've ever heard it used outside the context of records or CDs or disks in general. That's the type of thing I am looking for though, something that is used more to protect than to transport.

^{If you believe that one of the words I have mentioned is the best fit, please let me know. I feel they are not suited but am quite willing to accept I'm wrong on this one.}

Solution 1:

I think perhaps the term cosy is appropriate. A quick Google search reveals a number of items similar to your picture which are being marketed as a "phone cosy"

For example, a red knit Phone Cosy.

Another application of the term cosy is a tea cosy

Seems to me you might be looking at a ball cosy, although it is more of a neologism than a defined word.

Solution 2:

I immediately thought of a pouch:

noun -- a small bag or other flexible receptacle, typically carried in a pocket or attached to a belt

a tobacco pouch

Solution 3:

The term bag is used in US English for a wide variety of containers

a flexible container with an opening at one end

It also is routinely used to mean luggage and as part of the terms for specialized containers such as

• gym bag
• garbage bag
• feed bag
• punching bag
• goody bag
• laundry bag
• air sickness bag
• lunch bag

While these terms are not limited to spherical forms, they are often used to hold such objects.

An alternative is sack.