U+033B Combining Square Below

The Wikipedia has the following information about this codepoint:

A laminal consonant is a phone (speech sound) produced by obstructing the air passage with the blade of the tongue, the flat top front surface just behind the tip of the tongue in contact with upper lip, teeth, alveolar ridge, to possibly, as far back as the prepalatal arch, although in the last contact may involve parts behind the blade as well. It is distinct from an apical consonant, produced by creating an obstruction with the tongue apex (tongue tip) only. Sometimes laminal is used exclusively for an articulation that involves only the blade of the tongue with the tip being lowered and apicolaminal for an articulation that involves both the blade of the tongue and the raised tongue tip. The distinction applies only to coronal consonants, which use the front of the tongue.