Described embodiments include a system, method, and computer program product. A receiver circuit receives ultrasound echoes from at least two ultrasound-differentiable micro-objects implanted in a vertebrate subject (hereafter “implanted micro-objects”). A recognition circuit recognizes each implanted micro-object based upon a machine recognizable feature in the received echoes. A decoder circuit decodes pursuant to a conversion table each recognized implanted micro-objects into a digit of the base system of the conversion table. An aggregator circuit collects the decoded digits into a decoded data set. A computer storage media saves the decoded data set.
