What else ICMP is usde for?

The Internet Control Message Protocol (ICMP) is one of the main protocols of the Internet Protocol Suite. It is used by network devices, like routers, to send error messages indicating, for example, that a requested service is not available or that a host or router could not be reached.

ICMP errors will never be generated in response to an ICMP error message. If ICMP messages were sent in response to other ICMP messages, they would quickly multiply and create a storm of ICMP packets.
ICMP messages will never be sent in response to a broadcast or multicast addresses either, to prevent broadcast storms.