Can you ID these sensors for me? (Hop! Suitcase sensors)

Using Arduino Sensors
#1

Do you remember the Hop! Suitcase, the one that follows the Bluetooth signal in your cell phone around the airport?

Well, I found a picture of the Hop! in prototype. The pic has the sensors in view and I’m curious what they are. I expected to see antennas, but these look like microphones.

What do you think?

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#2

Ahhhh... They're ultrasonic senors. — Maxbotix Ultrasonic Rangefinder - LV-EZ1 [LV-EZ1] : ID 172 : $24.95 : Adafruit Industries, Unique & fun DIY electronics and kits

Guess the suitcase didn't triangulate the Bluetooth signal after all.

#3