It is very common for babies around 10 months old to explore their environment by mouthing or chewing on safe, rounded household items, especially when they are teething. This is typically a normal developmental phase and a way for them to soothe their gums. As long as the items are non-toxic, clean, and pose no choking risk, there is usually no need for concern; they will likely outgrow this phase as they develop new ways to play.