The pronoun that has no specific antecedent in the sentence is Something <u>because is an indefinite pronoun</u> and the indefinite pronouns do not require specific antecedents which means that those ones are used in place of nouns for people, things or amounts that are unknown or unnamed. They are: all, another, any, anybody, anyone, anything, both, each, either, enough, everybody, everyone, everything, few, fewer, less, little, many, more, most, much, neither, nobody, no one, nothing, none, one, other, others, several, some, somebody, someone, <u>something</u>, such, and they (people in general). So for the case of the sentence in mention, the Pronoun is Something.