I don’t think it’s a spider but it could be a decorative design or electronics.
Other anomalies in the image…
Mars Sol 1428 – Anomalies (The Spider) -1428ML0070630020602441E01
Was Life On Mars?
Mars Curiosity Rover Images – Sol 710 and more
I don’t think it’s a spider but it could be a decorative design or electronics.
Other anomalies in the image…