The murti is the point at which the English word idol becomes both inaccurate and loaded, because a consecrated image is, on the account the tradition gives of itself, not a representation but a residence.
Prana pratishtha
A murti is made to fixed iconographic rules and then consecrated in a rite, the prana pratishtha, understood to invite the deity to be present in it. That consecration is the difference between a murti and a statue. A consecrated murti is treated as a guest and a resident, woken, bathed, dressed, offered food, shown light and put to bed, and the word idol, given its history in colonial and missionary polemic, misses all of this.
Made to be dissolved
Some murtis are permanent and some are deliberately not. The clay Durga images of Bengal and the Ganesha images of Maharashtra are made for a festival, worshipped, and then immersed in water at its close, which is a considered statement about the temporary nature of form rather than a disposal. Deconsecration is a real procedure, and a damaged murti is not repaired and returned to use without it, which underlines that what is being handled is a presence with a beginning and an end rather than an object with a value.