"The Rocks of Janus" is Space Academy's contribution to this time-worn but trusty genre convention. If you recall, "Janus" was also the name of the Horta's planet in "Devil in the Dark," so you have to wonder if Space Academy scribe Samuel Peeples was paying some homage where homage was due.
Anyway, this episode of the 1970s Saturday morning kid's show finds the Academy in orbit of a giant planet, but two comets are fast approaching -- on a collision course with the space academy planetoid. Commander Gampu sends Blue Team in a Seeker to activate explosive charges and destroy the comets before they hit. But on the comet's surface, Laura and Chris and the others (including Peepo) find veins and arteries, and when one of the cadets attempts to hack off a sample, the rocks bleed. Turns out the whole comet is alive, a sick fella named Ergo. Peepo communicates with him and Ergo (in perfect English) tells the cadets "I forgive you...for chopping off pieces of me." Nice fella, this Ergo...
But Ergo is the least of the Academy's problems. Turns out that the other living rock (the other comet) is named "Targ." Targ is a criminal and wants to destroy everything, including the Academy and the seekere. Ergo would be able to stop him if he were at full strength, unfortunately he used the last of his free energy to enter the galaxy, and then the cadets started carving off samples. Fortunately, the cadets are able to strengthen Ergo by feeding him "magnetic flux," and at the end of the day, Targ is defeated and Ergo is taken back to the Academy to be healed.
"The Rocks of Janus" doesn't add much to the "silicon life-form" sci-fi TV convention. Like "Home Soil" (which came much later), the life form isn't detected until after humans have injured it. Like "All that Glisters," the good guys (in this case, from the Academy) seek to help out and do right after committing (an accidental). Otherwise, it's a familiar tale.
What else happens in this episode of Space Academy? Not much. Peepo yelps at one point, and sounds just like Michael Jackson. And we find out exactly what the Academy slang "Oraco!" means. "Order Received And Carried Out!"