"prayer rug" singular would require an article.
As it's unlikely there would be only one prayer rug, I'd suggest "prayer rugs are generally found."
I don't know if this suits the linked sentences and I've never been in a mosque.
You are right. I just think in turkish.
Because in Turkish although you tell in singular way, when you read you can understand that writer meant plural.
खूणचिठ्ठ्या
सर्व खूणचिठ्ठ्या पाहावाक्याचे मजकूर
परवाना: CC BY 2.0 FRनोंदवही
हे वाक्य मूळतः वाक्य क्र. 4411884
maydoo यांनी जोडले २७ जुलै, २०१५ रोजी
maydoo यांनी दुवा जोडला २७ जुलै, २०१५ रोजी
bandeirante यांनी दुवा जोडला २७ जुलै, २०१५ रोजी
maydoo यांनी संपादित केले २८ जुलै, २०१५ रोजी
Balamax यांनी दुवा जोडला ३० नोव्हेंबर, २०१६ रोजी